What does this PR do?

This PR fixes an issue where WebAssembly (.wasm) files were served with the incorrect MIME type (application/octet-stream) instead of application/wasm. This was causing problems for applications (e.g., Flutter Web) that rely on strict MIME type checking in browsers like Chrome.

The change introduces a specific check in the static file serving logic to ensure that files with a .wasm extension are explicitly served with the application/wasm MIME type.

Test Plan

A new E2E test, testStaticFileMimeTypes, has been added to tests/e2e/Services/Sites/SitesCustomServerTest.php. This test:

1. Deploys a static site containing a test.wasm file and an index.html file.
2. Makes a request to /test.wasm and asserts that the Content-Type header in the response is application/wasm.
3. Makes a request to /index.html and asserts that the Content-Type header contains text/html to ensure other file types are unaffected.

A minimal test.wasm file has been added to tests/resources/sites/static/ for testing purposes.

Related PRs and Issues

• Fixes an issue where .wasm files were served with incorrect MIME type.

Checklist

• Have you read the Contributing Guidelines on issues?
• If the PR includes a change to an API's metadata (desc, label, params, etc.), does it also include updated API specs and example docs?