Rework CHAdeMO support to more fully implement standard

[smaresca]

What This enhancement includes the appropriate CHAdeMO sequence for negotiation, connector locking and discharge support. Testing and further refinement is needed before this feature is entirely usable. Charging support is not yet present, though this PR lays the groundwork.

Why To enable CHAdeMO vehicles to function as a battery, while retaining the safety afforded by a connector with locking solenoid, contactor control, and similar.

How By implementing as much of the CHAdeMO standard as feasible given hardware limitation and access to closely-held specs.