fix: getRootDir behaviour for single directory causing wrong project root

[akaltar]

Linked issue: #7145

↪️ Pull Request

The getProjectRoot command was returning a wrong root when passed in a folder value. This caused the wrong project root to be determined when running in watch mode. In some cases this caused the entire filesystem to be watched.

The reason this is a draft is that this change breaks about ~100 integration tests, I'm happy to look into fixing those as well, but I'd like to first get feedback and confirm that my change aligns with the intended behaviour of the getProjectRoot function.

I tested this on a repo that was not working due to this bug, and now the .proxyrc.js file was loaded correctly and the site could be loaded. In fact some extra config files (.babelrc) also got loaded thanks to this.

Even if this is the intended change it's probably a huge breaking change, so please advise on how should I proceed.

Thank you for the amazing work on this project, adding a new test and making this fix was a breeze.

💻 Examples

Loading .proxyrc.js from project didn't work and explicitly setting the path for it wasn't possible.

🚨 Test instructions

✔️ PR Todo

• Added/updated unit tests for this change
• Filled out test instructions (In case there aren't any unit tests)
• Included links to related issues/PRs

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[mischnic]

Superseded by #7537