ovsdb: Allow a named-uuid to be used within the operation that creates it.

ovsdb: Allow a named-uuid to be used within the operation that creates it.

This allows a transaction like this:

[{"op": "insert",
  "table": "mytable",
  "row": {"i": 0, "k": ["named-uuid", "self"]},
  "uuid-name": "self"}]

It was already possible to do this by following up on the "insert" with an
"update", but since this was easy to implement I did it.