[enhancement] Mouse Controls? about emulatorjs

[michael-j-green]

@ethanaobrien; we might need to revisit that discussion on mouse capture.

Thinking we do this:

• provide an option to enable mouse capture on canvas click - this option should have a corresponding variable exposed to the host page (default false)
• if that first option is enabled, then provide another option to enable auto-capture - this option should have a corresponding variable exposed to the host page (default false)

Mouse capture is a requirement for many platforms, and mouse capture means that we don't have to do any funky scaling to match the host mouse movements to the emulation.

[ethanaobrien]

Yeah that works, we do also need to pass device ids to retroarch for lightgun/mouse related items too in the end

[michael-j-green]

Great :) I'll build out the mouse capture functions this week, but I'll have to have a chat with you around the device id component.

[michael-j-green]

Work to complete will be in #788