test: new qTest case to test the vhost-user-blk-server

test: new qTest case to test the vhost-user-blk-server

This test case has the same tests as tests/virtio-blk-test.c except for
tests have block_resize. Since the vhost-user-blk export only serves one
client one time, two exports are started by qemu-storage-daemon for the
hotplug test.

Suggested-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Coiby Xu <coiby.xu@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210309094106.196911-3-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210322092327.150720-2-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>