Implement FFI Result bindings for Jason API (#195)

[evdokimovs]

Synopsis

Продолжаем #204 и #205 расширяя список прокидываемых через FFI ошибок.

Solution

• [x] Throw Dart FormatExceptionss from RoomHandle.join() on provided token parse error.
• [x] Add RpcClientException thrown from ReconnectHandle's methods and RoomHandle.join()

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

Extend Rust to Dart error propagation (#198)

- throw FormatException from RoomHandle.join() and ReconnectHandle methods