Camera: Enable access to Request getParameters

- Modify the accessibility of Request.getParameters() to public to
enable access for request parameters in the extensions service. This
ensures that callbacks for previous requests, which might still be
firing while setParameters updates the parameters to the latest
request, can obtain the specific parameters for their respective requests.

Test: Camera CTS test
Bug: 315162244
Change-Id: I6e74d463895290df473e32ab62f3094144776577