* Check if a time interval is used in alert rules before deleting it
* Add time interval to parameters of ListAlertRulesQuery and ListNotificationSettings of DbStore
== Refacorings ==
* refactor isMuteTimeInUse to accept a single route
* update getMuteTiming to not return err
* update delete to get the mute timing from config first
* fix kind of TimeInterval
* register custom fields for selectors
* support field selectors in legacy storage
* support selectors in storage
===== Misc
* refactor conversions to build in one place
* hide implementation of provenance status behind accessors to use the key in selectors
* fix provenance error
* expose ngalert API to public
* add delete action to time-intervals
* introduce time-interval model generated by app-platform-sdk from CUE model the fields of the model are chosen to be compatible with the current model
* implement api server
* add feature flag alertingApiServer
---- Test Infra
* update helper to support creating custom users with enterprise permissions
* add generator for Interval model
Yuri Tseretyan
Alexander Zobnin