Add support for `[*]` in trusted hosts

[theyashl]

Summary

Fixed trusted host parsing for always trust case. This PR will fix allowing all networks upon passing --forwarded-allow-ips as * from gunicorn with uvicorn as a worker class.

The fix ensures that gunicorn integration and uvicorn as a standalone application will work fine for storing and validating trusted networks.

Complete RCA is present on issue: #2477

Checklist

• [x] I understand that this PR may be closed in case there was no previous discussion. (This doesn't apply to typos!)
• [x] I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• [x] I've updated the documentation accordingly.

[theyashl]

@Kludex requesting your review and inputs for this PR :)

[Kludex]

Please change the title as well.