[client side gp CLI] Message bus for port forwarding, local browser handling and clipboard sharing for SSH workflow

Is your feature request related to a problem? Please describe

The current SSH support is great, just needs a bit more integration.

Describe the behaviour you'd like

The following should work out-of-the-box:

• Auto port-forwarding (as in VSCode or Jetbrains)
• Cliboard sharing CLI between workspace<>local-machine. (e.g. gp clip, could be similar to pbcopy)

For example, to copy the contents of workspace a file into the clipboard register, I'd like to do cat <file> | gp clip and expect it to be copied in my local operating-system clipboard.

• gp preview <url> --external, it should communicate with the local gp CLI to spawn the default browser on user machine.

Describe alternatives you've considered

A SSH powered tiny implementation for auto port forwarding with tmux notifications (POC)

• https://github.com/axonasif/gssh

Additional context

Internal slack thread.

Start with the gp CLI's existing SSH workflow and review the linked gssh proof of concept for port-forwarding behavior. Define acceptance for automatic port forwarding, workspace-to-local clipboard streaming, and gp preview <url> --external opening the local browser, then verify each workflow end to end.