tests: qemublock: Add test case for detecting bitmaps as we create snapshots

tests: qemublock: Add test case for detecting bitmaps as we create snapshots

Add test data gathered from a run of qemu after creating bitmaps and
snapshots together in various combinations.

The following sequence of commands was used to achieve the
configuration:

virsh checkpoint-create-as VM --name a
virsh snapshot-create-as VM --disk-only
virsh snapshot-create-as VM --disk-only
virsh checkpoint-create-as VM --name b
virsh checkpoint-create-as VM --name c
virsh snapshot-create-as VM --disk-only
virsh checkpoint-create-as VM --name d
virsh snapshot-create-as VM --disk-only
virsh checkpoint-create-as VM --name current

Note that VM was restarted after these operations to allow renumbering
of the bitmaps in a more human-readable way.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>