Rewind support

[thenick775]

High Level Requirements:

• we want to be able to leverage rewind functionality across the gba core contract(s)

  • this functionality can be seen in the non-wasm mGBA implementations, among other cores SkyEmu also has this functionality

• we do not want this functionality to impact performance

  • may require threading through pthread -> web worker mechanisms (cross origin isolation required)

Rewind entails:

• being able to step backwards through frames by holding a button within the control panel
  • replays all actions+frames taken with an accuracy/timing equal to ~60fps
  • once the user stops rewinding the game should pick up from that point in time moving forwards (including all items such as sound, etc.)

This is fairly complex and may take some time to create the proper contract and feature support in the upstream core repositories, but I believe it can definitely be done. With this addition, my contract for the mGBA WASM core will be feature complete, where I would like to expand this same contract to other cores (see: #156)