Support asset/mesh/refquat (and refpos) in mujoco parser

[RussTedrake]

What happened?

As documented here.

I've only seen one model that uses it so far, but the shadow_dexee model in the mujoco menagerie is supposed to look like this:

but currently looks like this:

Version

No response

What operating system are you using?

No response

What installation option are you using?

No response

Relevant log output

[RussTedrake]

Changing to low priority, because I was able to handle it at the level of make_drake_compatible_model in the manipulation repo.