flowey: unify archive extraction

[jstarks]

bsdtar can extract just about everything. Don't have separate entry paths and tools for zip vs. tar.bz2 vs. some other thing in the future.

Also, ensure extraction verifies the target directory is still there, since users (like me) might delete it when it's in a bad state hoping that subsequent flowey invocations will re-extract it.

Finally, use the extract helpers for extracting (and thus caching) sysroot.tar.gz. This speeds repeated invocations of build-igvm.

This eliminates another weird apt package dependency.