Support connecting to another VM

[Octogonapus]

We can connect to another VM using the internal tools API. We should be able to present a list of VMs to the user and let them choose one to connect to. The UI for this should include a warning that the agent can't "disconnect" from the VM (although the debugger will detatch from the VM, any instrumented code will remain instrumented until the VM is stopped).

This will also require adding support for retransforming classes.