Add support for listing running processes

[nisargjhaveri]

Add support --list_processes, which lists the running processes on the device, along with PIDs.
This PID can be useful to attaching an already running process. Related #525.

The ability to list processes is provided by the com.apple.instruments.remoteserver service. This service uses a different communication protocol. The details and the reference implementation is provided by troybowman/ios_instruments_client. I've also referred the implementations at FBInstrumentsClient.m in facebook/idb and remote_server.py at doronz88/pymobiledevice3.

Ability to talk to the instruments server can also bring more improvements for us in future.

• Drastically improve speed for the --justlaunch argument by using the instruments server instead of launching via lldb and detaching.
• Add a subcommand to kill a running process.

All of these improvements can help with a bunch of use-cases and eliminate the need to use other tools along with ios-deploy for common debugging or simple automations for installing/launching apps.

Currently tested on one device with iOS 15.6.1

[gabebear]

This is super interesting, it will likely need some time to get tested by various usecases before being cut into a main release.