added manger to keep track of go routines in the services (#2869)

- added manager to wait for all go routines to end before exit
- code refactor
- renamed Manafer to Interface and GoRoutineManager to GroupManager
- replaced some go routine calls with manager Add func
- added unit tests for manager

pkg/utils/httpserver/server_test.go

@@ -12,9 +12,13 @@ import (
 	"go.uber.org/zap"
 
 	"github.com/fission/fission/pkg/utils/loggerfactory"
+	"github.com/fission/fission/pkg/utils/manager"
 )
 
 func TestStartServer(t *testing.T) {
+	mgr := manager.New()
+	defer mgr.Wait()
+
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 	logger := loggerfactory.GetLogger()
@@ -26,7 +30,10 @@ func TestStartServer(t *testing.T) {
 			logger.Error("failed to write response", zap.Error(err))
 		}
 	}))
-	go StartServer(ctx, logger, "test", "8999", m)
+
+	mgr.Add(ctx, func(ctx context.Context) {
+		StartServer(ctx, logger, mgr, "test", "8999", m)
+	})
 
 	tests := []struct {
 		Name       string