New feature 'sip mute' for muting worker non-webrtc calls

[chaosloth]

Summary

Add a mute button for non-WebRTC calls (i.e. Calls via SIP or PSTN). The default mute button requires the Voice SDK to be used as it calls the local method to mute, this plugin introduces a replacement UI button with a companion serverless function to mute the Flex worker by modifying the conference participants

Checklist

• Tested changes end to end
• Updated documentation
• Requested one or more reviewers

[chaosloth]

@dremin would you be so kind as to review, it's similar to the common serverless functions for conference-participant

[dremin]

I noticed the 'end call' button is also non-functional with a SIP phone. I think it would make a lot of sense to also address that in this feature (would need a different name), what do you think?

[dremin]

Could you also run npm run lint:fix to auto-fix and expose any further issues caught by the linter?
4 ESLint error(s) and 1 ESLint warning(s) found in pull request changed files.

[chaosloth]

TY @dremin Moving to new feature "sip-support" adding above changes

[chaosloth]

New PR with feature #350