Restructure cloudmigration service (#83211)

* Restructure cloudmigation service

* Adjust codewoners and wire

* Comment out unused metrics

pkg/services/cloudmigration/cloudmigrationimpl/store.go

@@ -0,0 +1,11 @@
+package cloudmigrationimpl
+
+import (
+	"context"
+
+	"github.com/grafana/grafana/pkg/services/cloudmigration"
+)
+
+type store interface {
+	MigrateDatasources(context.Context, *cloudmigration.MigrateDatasourcesRequest) (*cloudmigration.MigrateDatasourcesResponse, error)
+}