test(core): Add test to ensure Angular correctly detects paths when served from file system - #69221

Related to #53547

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular/blob/main/contributing-docs/commit-message-guidelines.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

Adds a test for #53547. I was asked to add one back then, but kind of forgot (better late than never). I think adding this regression test is important in an era where LLMs recklessly attempt to fix "vulnerabilities" for bug hunting bounties.

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• angular.dev application / infrastructure changes
• Other... Please describe: Test

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

• Yes
• No

Other information

I'm not sure if

Object.defineProperty(doc, 'baseURI', {
  value: 'file:///C:/Users/Test/Somewhere(2)/',
  configurable: true,
});

is the most canonical way to do this, but baseURI is readonly, but this is ultimately how the local file path is exposed.