fix(core/protocols): decorate service exceptions with unmodeled fields

[kuhe]

Issue

#7502

Description

Restores the addition of unmodeled fields onto ServiceException error objects.

Testing

• new tests for protocol error deserialization

Checklist

• If the PR is a feature, add integration tests (*.integ.spec.ts).
• 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?