RBAC: Split non-empty scopes into kind, attribute and identifier fields for better search performance (#71933)

* add a feature toggle

* add the fields for attribute, kind and identifier to permission

Co-authored-by: Kalle Persson <kalle.persson@grafana.com>

* set the new fields when new permissions are stored

* add migrations

Co-authored-by: Kalle Persson <kalle.persson@grafana.com>

* remove comments

* Update pkg/services/accesscontrol/migrator/migrator.go

Co-authored-by: Gabriel MABILLE <gamab@users.noreply.github.com>

* feedback: put column migrations behind the feature toggle, added an index, changed how wildcard scopes are split

* PR feedback: add a comment and revert an accidentally changed file

* PR feedback: handle the case with : in resource identifier

* switch from checking feature toggle through cfg to checking it through featuremgmt

* don't put the column migrations behind a feature toggle after all - this breaks permission queries from db

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Co-authored-by: Kalle Persson <kalle.persson@grafana.com>
Co-authored-by: Gabriel MABILLE <gamab@users.noreply.github.com>

pkg/services/featuremgmt/toggles_gen.csv

@@ -95,3 +95,4 @@ mlExpressions,experimental,@grafana/alerting-squad,false,false,false,false
 disableTraceQLStreaming,experimental,@grafana/observability-traces-and-profiling,false,false,false,true
 grafanaAPIServer,experimental,@grafana/grafana-app-platform-squad,false,false,false,false
 featureToggleAdminPage,experimental,@grafana/grafana-operator-experience-squad,false,false,true,false
+splitScopes,preview,@grafana/grafana-authnz-team,false,false,true,false