* MM-54238 Initial implementation
* MM-54238 Move websocket hook into app package
* MM-54238 Add tests for mentions in posted websocket messages
* Fix styling
* Fix other styling
* Idiomatic ID naming for new code
* Fix more styles
* Separate hooks to add mentions and followers
* Improved error handling for invalid types in hooks
* Rename HasChanges to ShouldProcess
* Pass broadcast hooks through hubStart
* Add test helper for asserting json unmarshaling
* Fix missing arguments in tests
* Ensure broadcast hooks are sent across the cluster and not to users
* Ensure tests actually cover following a post
* Fix code broken by merge
* Go vet again...
* Deep copy event before processing it with hooks
* Replace RemoveBroadcastHooks with WithoutBroadcastHooks
* Address feedback
* Add helper to fix type information for hook args
* Wrap WebSocketEvent and simplify BroadcastHook
* Address feedback
* Address feedback