Ophyd V2 devices: consider whether the current device_instantiation abstraction(s) are correct

[Tom-Willemsen]

For example, V2 devices don't necessarily take a prefix but have the prefix as part of the name.

We could:

• Say that all of our v2 devices take a prefix regardless, keeping consistency with v1
• Refactor device_instantiation to still be semi-generic but build name/prefix combinations correctly for v1 or v2 as appropriate
• Split device_instantiation into _v1 and _v2 with different behaviour.

Unclear to me exactly what is desirable.

[stan-dot]

@coretl this is relevant to #483 and can be either incorporated, closed, or still kept as-is

[coretl]

I think this can be closed as not relevant after #483

@DominicOram do you agree?

[DominicOram]

Yh, happy to close. Tbh we won't have any v1 devices round soon anyway