Add TestStand Image

[rdecarreau]

If you can run a teststand sequence in a docker container, now you can leverage the complex and powerful sequencing mechanisms and the sequence editor, which is one-of-a-kind, to create network-only sequences. This sounds limiting because you essentially have no hardware but there may be a lot of situations where network-only makes sense. e.g. TestStand driving VeriStand driving RT.