Recover Jason state after reconnection (#47, #27)

[evdokimovs]

Part of #47

Part of #27

Synopsis

When server tries to send an Event to a Web Client with closed RpcConnection Event wouldn't be sent or saved. In the current implementation, on sending Event with closed RpcConnection will be printed error log message.

Solution

Create observable Room snapshot at the Web Client side which will be updated by Media Server Events. When observable Room snapshot updates then real state should be updated. All updates will be performed only on this snapshot update. Events shouldn't update real state, but should update observable Room snapshot.

When Web Client reconnects to the server - server should send to the Web Client Event::RestoreState with a current Media Server's state. Web Client should set this snapshot
and based on this new snapshot, real state should be updated.

This PR implements only Web Client state restoring with Events which server should send but couldn't do it because lost RPC connection. Client's state restoring implementation will have minor changes in the next PR.

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

[evdokimovs]

FCM

Recover Jason state after reconnection (#100, #47, #27)

- add snapshot structures into medea-client-api-proto crate
- add observable snapshot structures into Jason
- implement client state restoring after RPC reconnection

Additionally:
- add observable collections to the medea-reactive crate

[alexlapa]

Resolved in #167