Modernized MuonDigitToRawBuffer

Requires Detector!207 (merged)

In particular :

• made it as functional as possible (will a DataHandle with update behavior there)
• dropped use of getDet

Can Muon people confirm that this code can be dropped ? @desimone @svecchi @satta

Could you also tell me whether MuonRec is actually used ? It's registered in Decoders.py, but I doubt it's used in practice.