test(angular): add angular 18 test app (#29456)

Issue number: N/A

---------

<!-- Please do not submit updates to dependencies unless it fixes an
issue. -->

<!-- Please try to limit your pull request to one type (bugfix, feature,
etc). Submit multiple pull requests if needed. -->

## What is the current behavior?
<!-- Please describe the current behavior that you are modifying. -->

Angular 18 will be releases ~ May 20th. Ionic Framework does not
currently have test infrastructure to check if the RC is compatible with
Ionic Framework.

## What is the new behavior?
<!-- Please describe the behavior or changes that are being added by
this PR. -->

- Adds an Angular 18 test app to the test infrastructure
- Added tech debt tickets for additional investigation and removing the
`--legacy-peer-deps` arg after v18 GA.

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

<!--
  If this introduces a breaking change:
1. Describe the impact and migration path for existing applications
below.
  2. Update the BREAKING.md file with the breaking change.
3. Add "BREAKING CHANGE: [...]" to the commit description when merging.
See
https://github.com/ionic-team/ionic-framework/blob/main/docs/CONTRIBUTING.md#footer
for more information.
-->


## Other information

<!-- Any other information that is important to this PR such as
screenshots of how the component looks before and after the change. -->

packages/angular/test/apps/ng18/server.ts

@@ -0,0 +1,71 @@
+
+import 'zone.js/node';
+
+import { APP_BASE_HREF } from '@angular/common';
+import { CommonEngine } from '@angular/ssr';
+import * as express from 'express';
+import { existsSync } from 'node:fs';
+import { join } from 'node:path';
+import bootstrap from './src/main.server';
+
+// The Express app is exported so that it can be used by serverless Functions.
+export function app(): express.Express {
+  const server = express();
+  const distFolder = join(process.cwd(), 'dist/test-app/browser');
+  const indexHtml = existsSync(join(distFolder, 'index.original.html'))
+    ? join(distFolder, 'index.original.html')
+    : join(distFolder, 'index.html');
+
+  const commonEngine = new CommonEngine();
+
+  server.set('view engine', 'html');
+  server.set('views', distFolder);
+
+  // Example Express Rest API endpoints
+  // server.get('/api/**', (req, res) => { });
+  // Serve static files from /browser
+  server.get('*.*', express.static(distFolder, {
+    maxAge: '1y'
+  }));
+
+  // All regular routes use the Angular engine
+  server.get('*', (req, res, next) => {
+    const { protocol, originalUrl, baseUrl, headers } = req;
+
+    commonEngine
+      .render({
+        bootstrap,
+        documentFilePath: indexHtml,
+        url: `${protocol}://${headers.host}${originalUrl}`,
+        publicPath: distFolder,
+        providers: [
+          { provide: APP_BASE_HREF, useValue: baseUrl },],
+      })
+      .then((html) => res.send(html))
+      .catch((err) => next(err));
+  });
+
+  return server;
+}
+
+function run(): void {
+  const port = process.env['PORT'] || 4000;
+
+  // Start up the Node server
+  const server = app();
+  server.listen(port, () => {
+    console.log(`Node Express server listening on http://localhost:${port}`);
+  });
+}
+
+// Webpack will replace 'require' with '__webpack_require__'
+// '__non_webpack_require__' is a proxy to Node 'require'
+// The below code is to ensure that the server is run only when not requiring the bundle.
+declare const __non_webpack_require__: NodeRequire;
+const mainModule = __non_webpack_require__.main;
+const moduleFilename = mainModule && mainModule.filename || '';
+if (moduleFilename === __filename || moduleFilename.includes('iisnode')) {
+  run();
+}
+
+export default bootstrap;