fix(middleware-user-agent): allow hash in userAgentAppId and propagate to inner clients

[kuhe]

Issue

#7439

Description

Confirmed with SDK org that propagation of the user agent app id to inner clients can be automatic.
Furthermore, we will not escape the # character in the app id.

Testing

new integration tests

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?