* introduce alerting notification app
* move code as is and remove from old registry
* update api server registration
* update make file and remove unnecessary args, copy some useful make commands from dashboards
* update codeowners
* move constants inside module and remove dependency from grafana
* add support for selectors to the app builder
* create notifications module and generate models
* switch template group to app models
* switch time intervals to use app models
* switch receiver to use app models
* switch routing tree to use app models
* move schema registration to resource packages
* fix package names to match app
* fix codeowners
* fix UI to use metadata.name instead of uid
* update dockerfile
* move generated models to pkg
* remove provenance from field selector
* move client factories to test files
* rename GenericClient to TypedClient
* Introduce new models RoutingTree, RouteDefaults and Route and api-server to serve them that is backed by provisioning notification policy service.
* update method UpdatePolicyTree of notification policy service to return route and new version
* declare new actions alert.notifications.routes:read and alert.notifications.routes:write and two corresponding fixed roles.
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Co-authored-by: Tom Ratcliffe <tom.ratcliffe@grafana.com>
Co-authored-by: Matthew Jacobson <matthew.jacobson@grafana.com>
