vm/qemu: implementing register collection optimization for QEMU diagnostics

[Babak Huseynov]

Hi,

I noticed a TODO comment in vm/qemu/qemu.go about optimizing register collection based on report types:
// TODO: we don't need registers on all reports. Probably only relevant for "crashes"
// (NULL derefs, paging faults, etc), but is not useful for WARNING/BUG/HANG (?).

I've implemented code that filters register dumps based on report.Type. Simply it is a switch-case conditional for checking whether Type provides any useful info for Diagnosis or not:
- warnings, hangs, and DoS reports;
- lock ordering issues (LOCKDEP);
- data race detection (KCSAN);
- memory leaks and so on.

I'm working on arm64 and it's not straightforward to me how to make presubmit.
Thus, I only checked on formal unit tests, linters and go fmt.

Is there anything I must consider before providing PR?

Thanks!