Introduce shared template for search inputs (#25338)

- Set
[type=search](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/search)
- Disable spellcheck
- Set maxLength 255 that I found in `templates/repo/issue/search.tmpl`
- Remove unnecessary `max-width`, it does nothing

---------

Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: Giteabot <teabot@gitea.io>

templates/shared/actions/runner_list.tmpl

@@ -35,8 +35,8 @@
 	<div class="ui attached segment">
 		<form class="ui form ignore-dirty" id="user-list-search-form" action="{{$.Link}}">
 			<!-- Search Text -->
-			<div class="ui fluid action input" style="max-width: 70%;">
-				<input name="q" value="{{.Keyword}}" placeholder="{{.locale.Tr "explore.search"}}..." autofocus>
+			<div class="ui fluid action input">
+				{{template "shared/searchinput" dict "locale" .locale "Value" .Keyword "AutoFocus" true}}
 				<button class="ui primary button">{{.locale.Tr "explore.search"}}</button>
 			</div>
 		</form>

templates/shared/searchinput.tmpl

@@ -0,0 +1 @@
+<input type="search" spellcheck="false" name="q" maxlength="255" placeholder="{{.locale.Tr "explore.search"}}…"{{if .Value}} value="{{.Value}}"{{end}}{{if .AutoFocus}} autofocus{{end}}{{if .Disabled}} disabled{{end}}>