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

core/stores/mon/options.go

@@ -0,0 +1,29 @@
+package mon
+
+import (
+	"time"
+
+	"github.com/zeromicro/go-zero/core/syncx"
+)
+
+var slowThreshold = syncx.ForAtomicDuration(defaultSlowThreshold)
+
+type (
+	options struct {
+		timeout time.Duration
+	}
+
+	// Option defines the method to customize a mongo model.
+	Option func(opts *options)
+)
+
+// SetSlowThreshold sets the slow threshold.
+func SetSlowThreshold(threshold time.Duration) {
+	slowThreshold.Set(threshold)
+}
+
+func defaultOptions() *options {
+	return &options{
+		timeout: defaultTimeout,
+	}
+}