Change Redis#exists calls to Redis#exists? to avoid deprecation warning (#14191)

.gitignore

Gemfile.lock

app/lib/activitypub/activity.rb

app/lib/activitypub/activity/move.rb

app/lib/feed_manager.rb

app/models/account_conversation.rb

app/models/encrypted_message.rb

app/models/home_feed.rb

app/workers/publish_announcement_reaction_worker.rb

app/workers/publish_scheduled_announcement_worker.rb

app/workers/unpublish_announcement_worker.rb

config/application.rb

config/initializers/redis.rb

lib/redis/namespace_extensions.rb