openhcl: storvsc integration tests

[juantian8seattle]

Integration tests for usermode storvsc using petri framework: boot, disk read/write, DVD, servicing save/restore.

Part of #273. Depends on #3096.

[mattkur]

A few comments:

(1) please add a plan to evaluate all of the current tests. I think you'll want to do that before you add new tests. This means changing the default command line in petri (for both openvmm and hyperv backends) to opt in with the new command line you stated.
(2) I think you'll get them by default, but there are a few things that you will want to explicitly check: (a) aarch64, (b) TDX, (c) AMD-SEV. Basically, these are the things that will benefit most from the usermode storvsc.