When the title in the issue has a value, set the text cursor at the end of the text. (#30090)

Fix:  [#25055](https://github.com/go-gitea/gitea/issues/25055)

Before

![image](https://github.com/go-gitea/gitea/assets/37935145/1b89cd7b-4fa3-49aa-9b5e-a8413add436e)

After

![image](https://github.com/go-gitea/gitea/assets/37935145/fa808f8d-d3ce-4245-a4fe-dd0282ba3fdf)

ps: I've noticed that we are gradually replacing jQuery, so I didn't use jQuery here.

templates/repo/issue/new_form.tmpl

@@ -9,7 +9,7 @@
 				{{ctx.AvatarUtils.Avatar .SignedUser 40}}
 				<div class="ui segment content tw-my-0">
 					<div class="field">
-						<input name="title" id="issue_title" placeholder="{{ctx.Locale.Tr "repo.milestones.title"}}" value="{{if .TitleQuery}}{{.TitleQuery}}{{else if .IssueTemplateTitle}}{{.IssueTemplateTitle}}{{else}}{{.title}}{{end}}" autofocus required maxlength="255" autocomplete="off">
+						<input name="title" class="js-autofocus-end" id="issue_title" placeholder="{{ctx.Locale.Tr "repo.milestones.title"}}" value="{{if .TitleQuery}}{{.TitleQuery}}{{else if .IssueTemplateTitle}}{{.IssueTemplateTitle}}{{else}}{{.title}}{{end}}" required maxlength="255" autocomplete="off">
 						{{if .PageIsComparePull}}
 							<div class="title_wip_desc" data-wip-prefixes="{{JsonUtils.EncodeToString .PullRequestWorkInProgressPrefixes}}">{{ctx.Locale.Tr "repo.pulls.title_wip_desc" (index .PullRequestWorkInProgressPrefixes 0)}}</div>
 						{{end}}

web_src/js/features/autofocus-end.js

@@ -0,0 +1,6 @@
+export function initAutoFocusEnd() {
+  for (const el of document.querySelectorAll('.js-autofocus-end')) {
+    el.focus(); // expects only one such element on one page. If there are many, then the last one gets the focus.
+    el.setSelectionRange(el.value.length, el.value.length);
+  }
+}

web_src/js/index.js

@@ -13,6 +13,7 @@ import {initImageDiff} from './features/imagediff.js';
 import {initRepoMigration} from './features/repo-migration.js';
 import {initRepoProject} from './features/repo-projects.js';
 import {initTableSort} from './features/tablesort.js';
+import {initAutoFocusEnd} from './features/autofocus-end.js';
 import {initAdminUserListSearchForm} from './features/admin/users.js';
 import {initAdminConfigs} from './features/admin/config.js';
 import {initMarkupAnchors} from './markup/anchors.js';
@@ -122,6 +123,7 @@ onDomReady(() => {
   initSshKeyFormParser();
   initStopwatch();
   initTableSort();
+  initAutoFocusEnd();
   initFindFileInRepo();
   initCopyContent();