Restructure cloudmigration service (#83211)

* Restructure cloudmigation service

* Adjust codewoners and wire

* Comment out unused metrics

pkg/services/cloudmigration/cloudmigrationimpl/cloudmigration_test.go

@@ -0,0 +1,15 @@
+package cloudmigrationimpl
+
+import (
+	"context"
+	"testing"
+
+	"github.com/grafana/grafana/pkg/services/cloudmigration"
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_NoopServiceDoesNothing(t *testing.T) {
+	s := &NoopServiceImpl{}
+	_, e := s.MigrateDatasources(context.Background(), &cloudmigration.MigrateDatasourcesRequest{})
+	assert.ErrorIs(t, e, cloudmigration.ErrFeatureDisabledError)
+}