Fix various bugs for "install" page (#23194)

## TLDR

* Fix the broken page / broken image problem when click "Install"
* Close #20089
* Fix the Password Hash Algorithm display problem for #22942
* Close #23183
* Close #23184

## Details

### The broken page / broken image problem when click "Install"
(Redirect failed after install gitea #23184)

Before: when click "install", all new requests will fail, because the
server has been restarted. Users just see a broken page with broken
images, sometimes the server is not ready but the user would have been
redirect to "/user/login" page, then the users see a new broken page
(connection refused or something wrong ...)

After: only check InstallLock=true for necessary handlers, and sleep for
a while before restarting the server, then the browser has enough time
to load the "post-install" page. And there is a script to check whether
"/user/login" is ready, the user will only be redirected to the login
page when the server is ready.

### During new instance setup make 'Gitea Base URL' filled from
window.location.origin #20089

If the "app_url" input contains `localhost` (the default value from
config), use current window's location href as the `app_url` (aka
ROOT_URL)

### Fix the Password Hash Algorithm display problem for "Provide the
ability to set password hash algorithm parameters #22942"

Before: the UI shows `pbkdf2$50000$50`

<details>

![image](https://user-images.githubusercontent.com/2114189/221917143-e1e54798-1698-4fee-a18d-00c48081fc39.png)

</details>

After: the UI shows `pbkdf2`

<details>

![image](https://user-images.githubusercontent.com/2114189/221916999-97a15be8-2ebb-4a01-bf93-dac18e354fcc.png)

</details>

### GET data: net::ERR_INVALID_URL #23183

Cause by empty `data:` in `<link rel="manifest"
href="data:{{.ManifestData}}">`

---------

Co-authored-by: Jason Song <i@wolfogre.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

web_src/js/features/install.js

@@ -2,10 +2,18 @@ import $ from 'jquery';
 import {hideElem, showElem} from '../utils/dom.js';
 
 export function initInstall() {
-  if ($('.page-content.install').length === 0) {
+  const $page = $('.page-content.install');
+  if ($page.length === 0) {
     return;
   }
+  if ($page.is('.post-install')) {
+    initPostInstall();
+  } else {
+    initPreInstall();
+  }
+}
 
+function initPreInstall() {
   const defaultDbUser = 'gitea';
   const defaultDbName = 'gitea';
 
@@ -40,6 +48,18 @@ export function initInstall() {
     } // else: for SQLite3, the default path is always prepared by backend code (setting)
   }).trigger('change');
 
+  const $appUrl = $('#app_url');
+  const configAppUrl = $appUrl.val();
+  if (configAppUrl.includes('://localhost')) {
+    $appUrl.val(window.location.href);
+  }
+
+  const $domain = $('#domain');
+  const configDomain = $domain.val().trim();
+  if (configDomain === 'localhost') {
+    $domain.val(window.location.hostname);
+  }
+
   // TODO: better handling of exclusive relations.
   $('#offline-mode input').on('change', function () {
     if ($(this).is(':checked')) {
@@ -83,3 +103,20 @@ export function initInstall() {
     }
   });
 }
+
+function initPostInstall() {
+  const el = document.getElementById('goto-user-login');
+  if (!el) return;
+
+  const targetUrl = el.getAttribute('href');
+  let tid = setInterval(async () => {
+    try {
+      const resp = await fetch(targetUrl);
+      if (tid && resp.status === 200) {
+        clearInterval(tid);
+        tid = null;
+        window.location.href = targetUrl;
+      }
+    } catch {}
+  }, 1000);
+}