Implement proper SDL encapsulation for emulator

[obrusvit]

Currently, the display driver and the drawing code using SDL resides in one file.

Proper encapsulation would enable to have source files responsible for drawing using SDL library exposing necessary functionality for

• separate code handling the display refresh using a reference to the SDL object
• separate code handling the LED
• separate code handling haptic feedback for emu, see Implement haptic support in emulator #3735

See a comment on the LED for emulator PR
See also this comment on the haptic for emulator PR