* refactor template service to contstruct notification template in one place, get provenance before creating and calculate resource version after.
* refactor get by UID and name
* introduce template kind in NotificationTemplate
* introduce includeImported flag and use in the k8s api
* support imported templates
* add kind to template uid
* tests for imported templates
* update API model
* set kind to default templates
* migrate to new manifest format
* rename app to alerting.notifications to not conflict with rules
* disable custom field selectors as they are not supported in appinstaller
Yuri Tseretyan
Alexander Akhmetov