Show outdated comments in files changed tab (#24936) (#25428)

Backport #24936

If enabled show a clickable label in the comment. A click on the label
opens the Conversation tab with the comment focussed - there you're able
to view the old diff (or original diff the comment was created on).

**Screenshots**


![image](63ab9571-a9ee-4900-9f02-94ab0095f9e7)


![image](78f7c225-8d76-46f5-acfd-9b8aab988a6c)

When resolved and outdated:


![image](6ece9ebd-c792-4aa5-9c35-628694e9d093)

Option to enable/disable this (stored in user settings - default is
disabled):


![image](ed99dfe4-76dc-4c12-bd96-e7e62da50ab5)


![image](e837a052-e92e-4a28-906d-9db5bacf93a6)

fixes #24913

Co-authored-by: silverwind <me@silverwind.io>

templates/repo/diff/comments.tmpl

@@ -31,6 +31,12 @@
 				{{end}}
 			</div>
 			<div class="comment-header-right actions gt-df gt-ac">
+				{{if .Invalidated}}
+					{{$referenceUrl := printf "%s#%s" $.root.Issue.Link .HashTag}}
+					<a href="{{AppSubUrl}}{{$referenceUrl}}" class="ui label basic small" data-tooltip-content="{{$.root.locale.Tr "repo.issues.review.outdated_description"}}">
+						{{$.root.locale.Tr "repo.issues.review.outdated"}}
+					</a>
+				{{end}}
 				{{if and .Review}}
 					{{if eq .Review.Type 0}}
 						<div class="ui label basic small yellow pending-label" data-tooltip-content="{{$.root.locale.Tr "repo.issues.review.pending.tooltip" ($.root.locale.Tr "repo.diff.review") ($.root.locale.Tr "repo.diff.review.approve") ($.root.locale.Tr "repo.diff.review.comment") ($.root.locale.Tr "repo.diff.review.reject")}}">