option to attach to a process tree

[tmm1]

would be nice if samply could take multiple -p options, or ideally be able to follow and attach to all child processes of the pid passed in

[tmm1]

appears this was part of the original design, so maybe no option is needed

samply/samply/src/mac/process_launcher.rs

Lines 326 to 332 in 36646f1

	// always root pid first
	queue_pid(pid, false);
	// TODO: find all its children
	ExistingProcessRunner {
	pid,

[tmm1]

it would also be nice to attach to new child processes automatically. is there any prior art there?