Demonstrate a record-level alternative motor interface

Instead of using motor record, demonstrate a record-level alternative (e.g. PREFIX:VELO instead of PREFIX.VELO) with the same behaviour. Make this same record-level interface in asyn model 3 drivers like pmac, and add support in Ophyd for this.

Start by tracing the existing motor-record interface and compare it with the proposed record-level form, such as PREFIX:VELO versus PREFIX.VELO. Then inspect the asyn model 3 drivers, including pmac, and the Ophyd integration; done means the alternative interface has the same behavior in those components.

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