DEV: move post flags into database (#27125)

This is preparation for a feature that will allow admins to define their custom flags. Current behaviour should stay untouched.

spec/models/flag_spec.rb

@@ -0,0 +1,69 @@
+# frozen_string_literal: true
+
+RSpec.describe Flag, type: :model do
+  before { Flag.reset_flag_settings! }
+
+  it "has id lower than 1000 for system flags" do
+    flag = Fabricate(:flag, id: 1)
+    expect(flag.system?).to be true
+  end
+
+  it "has id greater than 1000 for non-system flags" do
+    flag = Fabricate(:flag)
+    expect(flag.system?).to be false
+    expect(flag.id).to be > 1000
+  end
+
+  it "has correct name key" do
+    flag = Fabricate(:flag, name: "CuStOm Flag!!!")
+    expect(flag.name_key).to eq("custom_flag")
+
+    flag.update!(name: "It's Illegal")
+    expect(flag.name_key).to eq("its_illegal")
+
+    flag.update!(name: "THIS IS    SPaM!+)(*&^%$#@@@!)")
+    expect(flag.name_key).to eq("this_is_spam")
+  end
+
+  it "updates post action types when created, modified or destroyed" do
+    expect(PostActionType.flag_types.keys).to eq(
+      %i[notify_user notify_moderators off_topic inappropriate spam illegal],
+    )
+    expect(ReviewableScore.types.keys).to eq(
+      %i[notify_user notify_moderators off_topic inappropriate spam illegal needs_approval],
+    )
+
+    flag = Fabricate(:flag, name: "custom")
+    expect(PostActionType.flag_types.keys).to eq(
+      %i[notify_user notify_moderators off_topic inappropriate spam illegal custom],
+    )
+    expect(ReviewableScore.types.keys).to eq(
+      %i[notify_user notify_moderators off_topic inappropriate spam illegal custom needs_approval],
+    )
+
+    flag.update!(name: "edited_custom")
+    expect(PostActionType.flag_types.keys).to eq(
+      %i[notify_user notify_moderators off_topic inappropriate spam illegal edited_custom],
+    )
+    expect(ReviewableScore.types.keys).to eq(
+      %i[
+        notify_user
+        notify_moderators
+        off_topic
+        inappropriate
+        spam
+        illegal
+        edited_custom
+        needs_approval
+      ],
+    )
+
+    flag.destroy!
+    expect(PostActionType.flag_types.keys).to eq(
+      %i[notify_user notify_moderators off_topic inappropriate spam illegal],
+    )
+    expect(ReviewableScore.types.keys).to eq(
+      %i[notify_user notify_moderators off_topic inappropriate spam illegal needs_approval],
+    )
+  end
+end