Implement webhook branch filter (#7791)

* Fix validate() function to handle errors in embedded anon structs

* Implement webhook branch filter

See #2025, #3998.

modules/auth/repo_form.go

@@ -185,6 +185,7 @@ type WebhookForm struct {
 	PullRequest  bool
 	Repository   bool
 	Active       bool
+	BranchFilter string `binding:"GlobPattern"`
 }
 
 // PushOnly if the hook will be triggered when push