* 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
Ryan McKinley
Yuri Tseretyan
Todd Treece