Fixed remaining cop offenses for Naming/FileName

.rubocop.yml

app/views/issues/_issues_calendar.ics.ruby

bin/pngquant

ee/app/models/dast/branch.rb

ee/lib/elastic/v12p1/application_class_proxy.rb

ee/lib/elastic/v12p1/application_instance_proxy.rb

ee/lib/elastic/v12p1/config.rb

ee/lib/elastic/v12p1/issue_class_proxy.rb

ee/lib/elastic/v12p1/issue_instance_proxy.rb

ee/lib/elastic/v12p1/merge_request_class_proxy.rb

ee/lib/elastic/v12p1/merge_request_instance_proxy.rb

ee/lib/elastic/v12p1/milestone_class_proxy.rb

ee/lib/elastic/v12p1/milestone_instance_proxy.rb

ee/lib/elastic/v12p1/note_class_proxy.rb

ee/lib/elastic/v12p1/note_instance_proxy.rb

ee/lib/elastic/v12p1/project_class_proxy.rb

ee/lib/elastic/v12p1/project_instance_proxy.rb

ee/lib/elastic/v12p1/project_wiki_class_proxy.rb

ee/lib/elastic/v12p1/project_wiki_instance_proxy.rb

ee/lib/elastic/v12p1/repository_class_proxy.rb