Merge branch 'even-more-frozen-string-lib' into 'master'

.rubocop.yml

changelogs/unreleased/even-more-frozen-string-lib.yml

...ployment_migration/post_deployment_migration_generator.rb

lib/gitaly/server.rb

lib/google_api/auth.rb

lib/google_api/cloud_platform/client.rb

lib/haml_lint/inline_javascript.rb

lib/json_web_token/rsa_token.rb

lib/json_web_token/token.rb

lib/mattermost/client.rb

lib/mattermost/command.rb

lib/mattermost/error.rb

lib/mattermost/session.rb

lib/mattermost/team.rb

lib/microsoft_teams/activity.rb

lib/microsoft_teams/notifier.rb

lib/object_storage/direct_upload.rb

lib/omni_auth/strategies/bitbucket.rb

lib/omni_auth/strategies/jwt.rb

lib/peek/rblineprof/custom_controller_helpers.rb