Implement media muting/unmuting (#27)

[evdokimovs]

Part of #27

Requires #155

Synopsis

In #155 old mute/unmute mechanism was renamed to disable/enable. Now we need to implement new mute/unmute mechanism which will switch MediaStreamTrack.enabled field and doesn't requires renegotiation.

Solution

Abstract enable/disable logic and reuse it for new mutes/unmutes.

Checklist

• Created PR:
  • In draft mode
  • Name contains Draft: prefix
  • Name contains issue reference
  • Has k:: labels applied
  • Has assignee
• Documentation is updated (if required)
• Tests are updated (if required)
• Changes conform code style
• CHANGELOG entry is added (if required)
• FCM (final commit message) is posted
  • and approved
• Review is completed and changes are approved
• Before merge:
  • Milestone is set
  • PR's name and description are correct and up-to-date
  • Draft: prefix is removed
  • All temporary labels are removed

[tyranron]

Be more principal and careful with code style and docs.