Also:

- Fix locks not being removed when jobs go to the dead job queue
- Add UI for managing locks to the Sidekiq dashboard
- Remove unused Sidekiq workers

Fix #13349

* Remove Salmon and PubSubHubbub endpoints

* Add error when trying to follow OStatus accounts

* Fix new accounts not being created in ResolveAccountService

* Refactor imports

* Export show_reblogs when exporting list of followed users

* Add support for importing show_reblogs with following collection

* Fix tests

* Export hide_notifications along with user mutes

* Import hide_notifications along with muted users list

* Add headers for CSV exports