Fix Flutter upgrade to v3.22

[evdokimovs]

Synopsis

The Flutter team has recently released Flutter v3.22, leading to build error in Jason. Example of build error:

../lib/src/native/platform/peer_connection.dart:32:20: Error: Expected type 'void Function(PeerConnection)' to be 'void Function(Object)', which is the Dart type corresponding to 'NativeFunction<Void Function(Handle)>'.

Failed CI after Flutter release

Solution

Change signatures of FFI functions to accept Object instead of concrete types, and cast this Objects to concrete type with as keyword inside the function.

Checklist

• Created PR:
  • [x] In draft mode
  • [x] Name contains issue reference
  • [x] Has type and k:: labels applied
  • [x] Has assignee
• Before review:
  • [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 or updated
  • [x] Draft mode is removed
• [x] Review is completed and changes are approved
  • [x] FCM (final commit message) is approved
• Before merge:
  • [x] Milestone is set
  • [x] PR's name and description are correct and up-to-date
  • [x] All temporary labels are removed

[evdokimovs]

FCM

Upgrade to 3.22 Flutter version (#169)

Additionally:
- switch `MEDEA_TAG` to `edge` in CI spec