Feature/grpc support

[just-at-uber]

Added

• GRPC support is now available for Cadence UI. By default, to preserve backwards compatibility, the transportClientType will default to 'tchannel'. To switch to 'grpc', you have 1 of 2 options:
  • set environment variable TRANSPORT_CLIENT_TYPE = 'grpc'
  • set configuration passed to server on startup:

    app.init({
      transportClientType: 'grpc',
    }).listen(port)
    

• GRPC supported in integration tests. To test different configurations, see server/test/cadence-frontend-simulator.js : LN43 to adjust TRANSPORT_CLIENT_TYPE value

Changed

• TChannel mock is now separated into it's own file (similar to GRPC) for integration tests.
• Updated Cadence IDL commit hash to latest which contains new proto definitions for GRPC. This is now pulling two folders instead of just the thrift folder and directory references have been adjusted to compensate for this.