Rename mute/unmute to enable/disable (#27)

[evdokimovs]

Part of #27

Required for #156

Synopsis

It was decided that current muting mechanism more about MediaStreamTracks enabling/disabling, so muting/unmuting naming now out of date.

Solution

Rename all mute/unmute related things to enable/disable naming.

Checklist

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

[evdokimovs]

FCM

Rename mute/unmute to enable/disable (#155, #27)

Additionally:
- upgrade Firefox to 82.0.2 version for E2E tests