DEV: Convert min_trust_to_edit_post to groups (#24840)

We're changing the implementation of trust levels to use groups. Part of this is to have site settings that reference trust levels use groups instead. It converts the min_trust_to_edit_post site setting to edit_post_allowed_groups.

The old implementation will co-exist for a short period while I update any references in plugins and themes.

spec/lib/validators/post_validator_spec.rb

@@ -318,7 +318,7 @@ RSpec.describe PostValidator do
   end
 
   describe "force_edit_last_validator" do
-    fab!(:user)
+    fab!(:user) { Fabricate(:user, refresh_auto_groups: true) }
     fab!(:other_user) { Fabricate(:user) }
     fab!(:topic)