fix(issues): allow selecting a tag in the issue Branch/Tag dropdown (#39747)

* Fixes #39746
* Fixes #35505

The click handlers were bound only to the first `.reference-list-menu`
(branches), so clicking a tag did nothing. Bind them to the items of
both lists.

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

models/issues/issue.go

@@ -81,7 +81,7 @@ type Issue struct {
 	PullRequest       *PullRequest     `xorm:"-"`
 	NumComments       int
 
-	// TODO: RemoveIssueRef: see "repo/issue/branch_selector_field.tmpl"
+	// TODO: ISSUE-SIDEBAR-REF-SELECTOR: see "repo/issue/branch_selector_field.tmpl"
 	Ref string
 
 	PinOrder int `xorm:"-"` // 0 means not loaded, -1 means loaded but not pinned