Support DET-1B (and other?) LCD devices

[CaptainNic]

I think some of the models had different LCD layouts?

Yes, the DET-1B hardware uses a different LCD so it has a different layout. At some point, would be nice to be able to emulate other hardware. There is a clear FW version difference, e.g. 4.x is used on the DET-1B hardware, so that could be something we could guess at and/or add cmdline options to force.

Originally posted by @kbembedded in https://github.com/kbembedded/msemu/pull/57#issuecomment-706352757

May be a good idea to extract the LCD implementation into a separate place at first, then implement the other lcd devices against the same interface. Then the lcd device could be selected via some configuration when creating the msemu context.