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/storage/unified/resource/noop.go

@@ -35,6 +35,10 @@ func (n *noopService) Read(context.Context, *ReadRequest) (*ReadResponse, error)
 	return nil, ErrNotImplementedYet
 }
 
+func (n *noopService) Search(context.Context, *SearchRequest) (*SearchResponse, error) {
+	return nil, ErrNotImplementedYet
+}
+
 func (n *noopService) History(context.Context, *HistoryRequest) (*HistoryResponse, error) {
 	return nil, ErrNotImplementedYet
 }