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>

services/issue/issue.go

@@ -42,6 +42,20 @@ func ChangeTitle(issue *models.Issue, doer *models.User, title string) (err erro
 	return nil
 }
 
+// ChangeIssueRef changes the branch of this issue, as the given user.
+func ChangeIssueRef(issue *models.Issue, doer *models.User, ref string) error {
+	oldRef := issue.Ref
+	issue.Ref = ref
+
+	if err := issue.ChangeRef(doer, oldRef); err != nil {
+		return err
+	}
+
+	notification.NotifyIssueChangeRef(doer, issue, oldRef)
+
+	return nil
+}
+
 // UpdateAssignees is a helper function to add or delete one or multiple issue assignee(s)
 // Deleting is done the GitHub way (quote from their api documentation):
 // https://developer.github.com/v3/issues/#edit-an-issue