feat(sync): support for periodic repo sync in scale-out cluster (#2424)

This commit includes support for periodic repo sync in a scale-out
cluster.
Before this commit, all cluster members would sync all the repos as
the config is shared.

With this change, in periodic sync, the cluster member checks whether
it manages the repo. If it does not manage the repo, it will skip the
sync.

This commit also includes a unit test to test on-demand sync too, but
there are no logic changes for it as it is implicitly handled by the
proxying logic.

Signed-off-by: Vishwas Rajashekar <vrajashe@cisco.com>

pkg/extensions/sync/sync_internal_test.go

@@ -162,7 +162,7 @@ func TestService(t *testing.T) {
 			URLs: []string{"http://localhost"},
 		}
 
-		service, err := New(conf, "", os.TempDir(), storage.StoreController{}, mocks.MetaDBMock{}, log.Logger{})
+		service, err := New(conf, "", nil, os.TempDir(), storage.StoreController{}, mocks.MetaDBMock{}, log.Logger{})
 		So(err, ShouldBeNil)
 
 		err = service.SyncRepo(context.Background(), "repo")
@@ -176,7 +176,7 @@ func TestSyncRepo(t *testing.T) {
 			URLs: []string{"http://localhost"},
 		}
 
-		service, err := New(conf, "", os.TempDir(), storage.StoreController{}, mocks.MetaDBMock{}, log.Logger{})
+		service, err := New(conf, "", nil, os.TempDir(), storage.StoreController{}, mocks.MetaDBMock{}, log.Logger{})
 		So(err, ShouldBeNil)
 
 		service.remote = mocks.SyncRemote{