Direct avatar rendering (#13649)

* Direct avatar rendering

This adds new template helpers for avatar rendering which output image
elements with direct links to avatars which makes them cacheable by the
browsers.

This should be a major performance improvment for pages with many avatars.

* fix avatars of other user's profile pages

* fix top border on user avatar name

* uncircle avatars

* remove old incomplete avatar selector

* use title attribute for name and add it back on blame

* minor refactor

* tweak comments

* fix url path join and adjust test to new result

* dedupe functions

templates/repo/issue/list.tmpl

@@ -70,7 +70,9 @@
 						<div class="menu">
 							<a class="item" href="{{$.Link}}?q={{$.Keyword}}&type={{$.ViewType}}&sort={{$.SortType}}&state={{$.State}}&labels={{.SelectLabels}}&milestone={{$.MilestoneID}}">{{.i18n.Tr "repo.issues.filter_assginee_no_select"}}</a>
 							{{range .Assignees}}
-								<a class="{{if eq $.AssigneeID .ID}}active selected{{end}} item" href="{{$.Link}}?type={{$.ViewType}}&sort={{$.SortType}}&state={{$.State}}&labels={{$.SelectLabels}}&milestone={{$.MilestoneID}}&assignee={{.ID}}"><img src="{{.RelAvatarLink}}"> {{.GetDisplayName}}</a>
+								<a class="{{if eq $.AssigneeID .ID}}active selected{{end}} item" href="{{$.Link}}?type={{$.ViewType}}&sort={{$.SortType}}&state={{$.State}}&labels={{$.SelectLabels}}&milestone={{$.MilestoneID}}&assignee={{.ID}}">
+									{{avatar .}}
+								</a>
 							{{end}}
 						</div>
 					</div>
@@ -173,7 +175,7 @@
 							</div>
 							{{range .Assignees}}
 								<div class="item issue-action" data-element-id="{{.ID}}" data-url="{{$.RepoLink}}/issues/assignee">
-									<img src="{{.RelAvatarLink}}"> {{.GetDisplayName}}
+									{{avatar .}}
 								</div>
 							{{end}}
 						</div>