Merge commit 'dc09c10fa8cc9230bf14e48d790c8f0c26043f8f' into glitch-soc/merge-upstream

Conflicts:
- `.rubocop_todo.yml`:
  Upstream re-generated the file, while glitch-soc has a specific ignore
  for some file.
  Updated the file as upstream did and kept our extra ignore.
- `config/webpack/shared.js`:
  Upstream added a plugin, but our files are pretty different.
  Added the plugin as well.
- `spec/helpers/application_helper_spec.rb`:
  Upstream refactored tests, but part of them were different because
  of glitch-soc's theming system.
  Applied the refactoring to glitch-soc's change.

spec/helpers/application_helper_spec.rb

@@ -31,10 +31,7 @@ describe ApplicationHelper do
     context 'with a body class string from a controller' do
       before do
         without_partial_double_verification do
-          allow(helper).to receive(:body_class_string).and_return('modal-layout compose-standalone')
-          allow(helper).to receive(:current_flavour).and_return('glitch')
-          allow(helper).to receive(:current_skin).and_return('default')
-          allow(helper).to receive(:current_account).and_return(Fabricate(:account))
+          allow(helper).to receive_messages(body_class_string: 'modal-layout compose-standalone', current_flavour: 'glitch', current_skin: 'default', current_account: Fabricate(:account))
         end
       end