Add Alpha ESPlay Micro Target

[Cralex]

Although not yet ready for public release, the ESPlay Micro target is stable and mostly playable. See notes in the target file for details on the missing buttons and battery functionality.

[ducalex]

I'm beginning to think that we should move the lcd init sequence to the target definition somehow, having to edit rg_display.c for every target isn't great.

But we'll look into that later, for now I see nothing wrong with merging the PR as is :).

Thanks!