fix(cloudfront-signer): encode uri components in base url

[kuhe]

Issue

#7428
and related to #7237

Description

in the cloudfront signer, encode search params contained in the base URL. This is more consistent with the URL object normalization that was occurring earlier.

Testing

unit tests

Checklist

• If the PR is a feature, add integration tests (*.integ.spec.ts).
  • unit tests are able to exercise the full public API of the signer
• If you wrote E2E tests, are they resilient to concurrent I/O?
• If adding new public functions, did you add the @public tag and enable doc generation on the package?