[services] Tunnelbroker - Update Tunnelbroker protobuf file with ping and new device token in bidirectional stream

Summary:
This diff introduces an update of Tunnelbroker protobuf bidirectional stream MessagesStream with the ping and device token fields.

In ENG-1766 we created pinging messages to make sure the client is online. Currently, we are using it in a unidirectional Get, but we should add it to the bidirectional MessagesStream as it will replace the Send and Get methods.

In ENG-1782 we've added the mechanism of requesting new device notification tokens. Currently, we are requesting it in the Get message and expecting it in Send from the client. These two fields must be merged into the bidirectional MessagesStream because Get and Send will be deprecated in a favor of one bidirectional MessagesStream.

Related Linear task: ENG-2043

Test Plan: Protobuf file compilation is successful.

Reviewers: jon, tomek, varun, ashoat

Reviewed By: jon, tomek, ashoat

Subscribers: ashoat, tomek, atul, abosh

Differential Revision: https://phab.comm.dev/D5361