Merge branch 'main' into glitch-soc/merge-upstream

Conflicts:
- `app/models/account.rb`:
  Not a real conflict, just upstream getting rid of unused constants too close
  to glitch-soc-specific contents.
  Removed unused constants like upstream did.
- `app/models/trends.rb`:
  Conflict because glitch-soc disabled email notifications for trending links.
  Upstream has refactored this quite a bit and added trending posts.
  Took upstream code, but disabling the extra trending stuff will come in
  another commit.
- `app/views/admin/trends/links/index.html.haml`:
  Conflict due to glitch-soc's theming system.
  Ported upstream changes accordingly.

Gemfile

@@ -18,7 +18,7 @@ gem 'makara', '~> 0.5'
 gem 'pghero', '~> 2.8'
 gem 'dotenv-rails', '~> 2.7'
 
-gem 'aws-sdk-s3', '~> 1.112', require: false
+gem 'aws-sdk-s3', '~> 1.113', require: false
 gem 'fog-core', '<= 2.1.0'
 gem 'fog-openstack', '~> 0.3', require: false
 gem 'kt-paperclip', '~> 7.1'