iotests.py: Filters for VM.run_job()

iotests.py: Filters for VM.run_job()

Allow filters for VM.run_job(), and pass the filters given to
VM.blockdev_create() to it.

(Use this opportunity to annotate VM.run_job()'s parameter types;
unfortunately, for the filter, I could not come up with anything better
than Callable[[Any], Any] that would pass mypy's scrutiny.)

At one point, a plain string is logged, so the filters passed to it must
work fine with plain strings.  The only filters passed to it at this
point are the ones from VM.blockdev_create(), which are
filter_qmp_test_files() (by default) and 207's filter_hash().  Both
cannot handle plain strings yet, but we can make them by amending
filter_qmp() to treat them as plain values with a None key.

Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220318125304.66131-2-hreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>