Grafana Indexing PoC: Adds feature flag and gRPC endpoint (#93356)

* adds Filter gRPC and make protobuf

* adds route for querying the filter gRPC

* wires up Filter gRPC call

* [WIP] index from start

* renames gRPC endpoint to "Search"

* adds /apis/search route into k8s routes. Hacky for now.

* updates readme - wrong casing

* adds feature toggle for unified storage search

* hides US search behind feature flag. Clean up print statements.

* removes indexer - will be added in another PR

* Search: Add API Builder

* adds required method

* implementing UpdateAPIGroupInfo (WIP)

* adds groupversion

* commenting out for now

* remove unneeded code from experimenting and update register.go to match interface required

* namespaces search route

---------

Co-authored-by: leonorfmartins <leonorfmartins@gmail.com>
Co-authored-by: Todd Treece <todd.treece@grafana.com>

pkg/registry/apis/apis.go

@@ -15,6 +15,7 @@ import (
 	"github.com/grafana/grafana/pkg/registry/apis/playlist"
 	"github.com/grafana/grafana/pkg/registry/apis/query"
 	"github.com/grafana/grafana/pkg/registry/apis/scope"
+	"github.com/grafana/grafana/pkg/registry/apis/search"
 )
 
 var (
@@ -37,6 +38,7 @@ func ProvideRegistryServiceSink(
 	_ *scope.ScopeAPIBuilder,
 	_ *query.QueryAPIBuilder,
 	_ *notifications.NotificationsAPIBuilder,
+	_ *search.SearchAPIBuilder,
 ) *Service {
 	return &Service{}
 }