feat: use mongodb official driver instead of mgo (#1782)

* wip: backup

* wip: backup

* wip: backup

* backup

* backup

* backup

* add more tests

* fix wrong dependency

* fix lint errors

* remove test due to data race

* add tests

* fix test error

* add mon.Model

* add mon.Model unmarshal

* add monc

* add more tests for monc

* add more tests for monc

* add docs for mon and monc packages

* fix doc errors

* chhore: add comment

* chore: fix test bug

* chore: refine tests

* chore: remove primitive.NewObjectID in test code

* chore: rename test files for typo

rest/handler/timeouthandler_test.go

@@ -122,7 +122,7 @@ func TestTimeoutWriteBadCode(t *testing.T) {
 func TestTimeoutClientClosed(t *testing.T) {
 	timeoutHandler := TimeoutHandler(time.Minute)
 	handler := timeoutHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		w.WriteHeader(1000)
+		w.WriteHeader(http.StatusServiceUnavailable)
 	}))
 
 	req := httptest.NewRequest(http.MethodGet, "http://localhost", nil)