Rename `flutter_webrtc` dependency

[SleepySquash]

Synopsis

This PR renames flutter_webrtc dependency to its new name medea_flutter_webrtc, as importing medea_jason currently raises the following errors:

Error on line 1, column 7: "name" field doesn't match expected name "flutter_webrtc".
  ╷
1 │ name: medea_flutter_webrtc
  │       ^^^^^^^^^^^^^^^^^^^^
  ╵

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
  • [ ] 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

[SleepySquash]

FCM

Rename `flutter_webrtc` dependency to `medea_flutter_webrtc` (#73)