Only show relevant repositories on explore page (#19361)

Adds a new option to only show relevant repo's on the explore page, for bigger Gitea instances like Codeberg this is a nice option to enable to make the explore page more populated with unique and "high" quality repo's. A note is shown that the results are filtered and have the possibility to see the unfiltered results.

Co-authored-by: vednoc <vednoc@protonmail.com>
Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: 6543 <6543@obermui.de>

templates/explore/repo_search.tmpl

@@ -29,4 +29,9 @@
 		<button class="ui primary button">{{.locale.Tr "explore.search"}}</button>
 	</div>
 </form>
+{{if .OnlyShowRelevant}}
+	<div class="ui blue attached message explore-relevancy-note">
+		<span class="ui tooltip" data-content="{{.locale.Tr "explore.relevant_repositories_tooltip"}}">{{.locale.Tr "explore.relevant_repositories" ((printf "%s%s" $.Link "?no_filter=1")|Escape) | Safe}}</span>
+	</div>
+{{end}}
 <div class="ui divider"></div>