DEV: properly namespace chat (#20690)

This commit main goal was to comply with Zeitwerk and properly rely on autoloading. To achieve this, most resources have been namespaced under the `Chat` module.

- Given all models are now namespaced with `Chat::` and would change the stored types in DB when using polymorphism or STI (single table inheritance), this commit uses various Rails methods to ensure proper class is loaded and the stored name in DB is unchanged, eg: `Chat::Message` model will be stored as `"ChatMessage"`, and `"ChatMessage"` will correctly load `Chat::Message` model.
- Jobs are now using constants only, eg: `Jobs::Chat::Foo` and should only be enqueued this way

Notes:
- This commit also used this opportunity to limit the number of registered css files in plugin.rb
- `discourse_dev` support has been removed within this commit and will be reintroduced later

<!-- NOTE: All pull requests should have tests (rspec in Ruby, qunit in JavaScript). If your code does not include test coverage, please include an explanation of why it was omitted. -->

plugins/chat/spec/queries/chat/channel_memberships_query_spec.rb

@@ -2,7 +2,7 @@
 
 require "rails_helper"
 
-describe ChatChannelMembershipsQuery do
+describe Chat::ChannelMembershipsQuery do
   fab!(:user_1) { Fabricate(:user, username: "Aline", name: "Boetie") }
   fab!(:user_2) { Fabricate(:user, username: "Bertrand", name: "Arlan") }
 
@@ -23,8 +23,16 @@ describe ChatChannelMembershipsQuery do
 
       context "when memberships exist" do
         before do
-          UserChatChannelMembership.create(user: user_1, chat_channel: channel_1, following: true)
-          UserChatChannelMembership.create(user: user_2, chat_channel: channel_1, following: true)
+          Chat::UserChatChannelMembership.create(
+            user: user_1,
+            chat_channel: channel_1,
+            following: true,
+          )
+          Chat::UserChatChannelMembership.create(
+            user: user_2,
+            chat_channel: channel_1,
+            following: true,
+          )
         end
 
         it "returns the memberships" do
@@ -45,7 +53,11 @@ describe ChatChannelMembershipsQuery do
 
         context "when membership exists" do
           before do
-            UserChatChannelMembership.create(user: user_1, chat_channel: channel_1, following: true)
+            Chat::UserChatChannelMembership.create(
+              user: user_1,
+              chat_channel: channel_1,
+              following: true,
+            )
           end
 
           it "lists the user" do
@@ -89,7 +101,11 @@ describe ChatChannelMembershipsQuery do
       context "when user is not in group" do
         context "when membership exists" do
           before do
-            UserChatChannelMembership.create(user: user_1, chat_channel: channel_1, following: true)
+            Chat::UserChatChannelMembership.create(
+              user: user_1,
+              chat_channel: channel_1,
+              following: true,
+            )
           end
 
           it "doesn’t list the user" do
@@ -135,8 +151,16 @@ describe ChatChannelMembershipsQuery do
       fab!(:channel_1) { Fabricate(:category_channel) }
 
       before do
-        UserChatChannelMembership.create(user: user_1, chat_channel: channel_1, following: true)
-        UserChatChannelMembership.create(user: user_2, chat_channel: channel_1, following: true)
+        Chat::UserChatChannelMembership.create(
+          user: user_1,
+          chat_channel: channel_1,
+          following: true,
+        )
+        Chat::UserChatChannelMembership.create(
+          user: user_2,
+          chat_channel: channel_1,
+          following: true,
+        )
       end
 
       describe "offset param" do
@@ -160,8 +184,16 @@ describe ChatChannelMembershipsQuery do
       fab!(:channel_1) { Fabricate(:category_channel) }
 
       before do
-        UserChatChannelMembership.create(user: user_1, chat_channel: channel_1, following: true)
-        UserChatChannelMembership.create(user: user_2, chat_channel: channel_1, following: true)
+        Chat::UserChatChannelMembership.create(
+          user: user_1,
+          chat_channel: channel_1,
+          following: true,
+        )
+        Chat::UserChatChannelMembership.create(
+          user: user_2,
+          chat_channel: channel_1,
+          following: true,
+        )
       end
 
       it "filters the results" do
@@ -176,8 +208,16 @@ describe ChatChannelMembershipsQuery do
       fab!(:channel_1) { Fabricate(:category_channel) }
 
       before do
-        UserChatChannelMembership.create(user: user_1, chat_channel: channel_1, following: true)
-        UserChatChannelMembership.create(user: user_2, chat_channel: channel_1, following: true)
+        Chat::UserChatChannelMembership.create(
+          user: user_1,
+          chat_channel: channel_1,
+          following: true,
+        )
+        Chat::UserChatChannelMembership.create(
+          user: user_2,
+          chat_channel: channel_1,
+          following: true,
+        )
       end
 
       context "when prioritizes username in ux is enabled" do
@@ -220,7 +260,11 @@ describe ChatChannelMembershipsQuery do
     fab!(:staged_user) { Fabricate(:staged) }
 
     before do
-      UserChatChannelMembership.create(user: staged_user, chat_channel: channel_1, following: true)
+      Chat::UserChatChannelMembership.create(
+        user: staged_user,
+        chat_channel: channel_1,
+        following: true,
+      )
     end
 
     it "doesn’t list staged users" do
@@ -236,7 +280,7 @@ describe ChatChannelMembershipsQuery do
     end
 
     before do
-      UserChatChannelMembership.create(
+      Chat::UserChatChannelMembership.create(
         user: suspended_user,
         chat_channel: channel_1,
         following: true,
@@ -254,7 +298,7 @@ describe ChatChannelMembershipsQuery do
     fab!(:inactive_user) { Fabricate(:inactive_user) }
 
     before do
-      UserChatChannelMembership.create(
+      Chat::UserChatChannelMembership.create(
         user: inactive_user,
         chat_channel: channel_1,
         following: true,

plugins/chat/spec/queries/chat/channel_unreads_query_spec.rb

@@ -2,7 +2,7 @@
 
 require "rails_helper"
 
-describe ChatChannelUnreadsQuery do
+describe Chat::ChannelUnreadsQuery do
   fab!(:channel_1) { Fabricate(:category_channel) }
   fab!(:current_user) { Fabricate(:user) }
 
@@ -33,7 +33,7 @@ describe ChatChannelUnreadsQuery do
           user_id: current_user.id,
           data: { chat_message_id: message.id, chat_channel_id: channel_1.id }.to_json,
         )
-      ChatMention.create!(notification: notification, user: current_user, chat_message: message)
+      Chat::Mention.create!(notification: notification, user: current_user, chat_message: message)
 
       expect(described_class.call(channel_id: channel_1.id, user_id: current_user.id)).to eq(
         { mention_count: 1, unread_count: 0 },