[lib] implement sending message to Tunnelbroker

Summary:
ENG-8347

Add callback to send message to Tunnelbroker.

Depends on D12523

Test Plan:
Call this from both web and native:

const message: SetDeviceToken = {
  type: messageToTunnelbrokerTypes.SET_DEVICE_TOKEN,
  deviceToken: 'token',
};
 await sendMessageToTunnelbroker(JSON.stringify(message));

and verify if deviceToken is persisted in DDB.

Reviewers: bartek, marcin

Reviewed By: bartek

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D12524