Create the `polykey nodes join` command

[aryanjassal]

Specification

The polykey nodes join command is supposed to switch the active network to the target network. An RPC handler wrapping the syncNodeGraphHandlerfunction is being worked upon in MatrixAI/Polykey#923. This new RPC handler should be used by the command to switch networks.

Additional context

• Allow agent to join a network using network access tokens Polykey#923

Tasks

1. Create polykey nodes join command
2. Use the created handler to switch networks
3. Add tests confirming this behaviour

[linear]

ENG-644