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>

models/issue.go

@@ -709,6 +709,22 @@ func (issue *Issue) ChangeTitle(doer *User, oldTitle string) (err error) {
 	return sess.Commit()
 }
 
+// ChangeRef changes the branch of this issue, as the given user.
+func (issue *Issue) ChangeRef(doer *User, oldRef string) (err error) {
+	sess := x.NewSession()
+	defer sess.Close()
+
+	if err = sess.Begin(); err != nil {
+		return err
+	}
+
+	if err = updateIssueCols(sess, issue, "ref"); err != nil {
+		return fmt.Errorf("updateIssueCols: %v", err)
+	}
+
+	return sess.Commit()
+}
+
 // AddDeletePRBranchComment adds delete branch comment for pull request issue
 func AddDeletePRBranchComment(doer *User, repo *Repository, issueID int64, branchName string) error {
 	issue, err := getIssueByID(x, issueID)