DEV: Convert min_trust_to_create_topic to groups (#24740)

This change converts the min_trust_to_create_topic site setting to
create_topic_allowed_groups.

See: https://meta.discourse.org/t/283408

- Hides the old setting
- Adds the new site setting
- Add a deprecation warning
- Updates to use the new setting
- Adds a migration to fill in the new setting if the old setting was
changed
- Adds an entry to the site_setting.keywords section
- Updates tests to account for the new change
- After a couple of months, we will remove the min_trust_to_create_topicsetting entirely.

Internal ref: /t/117248

spec/lib/post_creator_spec.rb

@@ -4,10 +4,10 @@ require "post_creator"
 require "topic_subtype"
 
 RSpec.describe PostCreator do
-  fab!(:user)
-  fab!(:admin)
-  fab!(:coding_horror)
-  fab!(:evil_trout)
+  fab!(:user) { Fabricate(:user, refresh_auto_groups: true) }
+  fab!(:admin) { Fabricate(:admin, refresh_auto_groups: true) }
+  fab!(:coding_horror) { Fabricate(:coding_horror, refresh_auto_groups: true) }
+  fab!(:evil_trout) { Fabricate(:evil_trout, refresh_auto_groups: true) }
   let(:topic) { Fabricate(:topic, user: user) }
 
   describe "new topic" do
@@ -1578,7 +1578,7 @@ RSpec.describe PostCreator do
   end
 
   describe "staged users" do
-    fab!(:staged)
+    fab!(:staged) { Fabricate(:staged, refresh_auto_groups: true) }
 
     it "automatically watches all messages it participates in" do
       post =
@@ -2065,9 +2065,9 @@ RSpec.describe PostCreator do
   end
 
   describe "#create_post_notice" do
-    fab!(:user)
-    fab!(:staged)
-    fab!(:anonymous)
+    fab!(:user) { Fabricate(:user, refresh_auto_groups: true) }
+    fab!(:staged) { Fabricate(:staged, refresh_auto_groups: true) }
+    fab!(:anonymous) { Fabricate(:anonymous, refresh_auto_groups: true) }
 
     it "generates post notices for new users" do
       post =