Change/remove a branch of an open issue (#9080)

* Add field with isIssueWriter to front end

* Make branch field editable

* Switch frontend to form and POST from javascript

* Add /issue/id/ref endpoint to routes

* Use UpdateIssueTitle model to change ref in backend

* Removed crossreference check and adding comments on branch change

* Use ref returned from POST to update the field

* Prevent calling loadRepo from models/

* Branch/tag refreshed without page reload

* Remove filter for empty branch name

* Add clear option to tag list as well

* Delete button translation and coloring

* Fix for not showing selected branch name in new issue

* Check that branch is not being changed on a PR

* Change logic

* Notification when changing issue ref

* Fix for renamed permission parameter

* Fix for failing build

* Apply suggestions from code review

Co-authored-by: zeripath <art27@cantab.net>

Co-authored-by: Gitea <gitea@fake.local>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

routers/routes/routes.go

@@ -733,6 +733,7 @@ func RegisterRoutes(m *macaron.Macaron) {
 				m.Post("/title", repo.UpdateIssueTitle)
 				m.Post("/content", repo.UpdateIssueContent)
 				m.Post("/watch", repo.IssueWatch)
+				m.Post("/ref", repo.UpdateIssueRef)
 				m.Group("/dependency", func() {
 					m.Post("/add", repo.AddDependency)
 					m.Post("/delete", repo.RemoveDependency)