propolis-server HTTP API versioning + phd = ow #980
Description
as experienced in #977: https://github.com/oxidecomputer/propolis/pull/977/files#r2582502490
I'm not even sure if we can nicely discover what the latest supported API for a propolis-server is, from just a git hash for base. but we'll want to pick a different client for the older API so we can drive the base propolis at all in these tests! (un)fortunately this has no relationship to the actual ability to migrate, which should work regardless.