Sega Megadrive/Genesis - allow choosing gamepad type in bml file or through CLI

[Tartifless]

Is your feature request related to a problem? Please describe.
When using ARES through command line, or through a launcher, or on a setup without keyboard / mouse, it is impossible to switch gamepad type to fighting pad or 6-button pad for megadrive/genesis, as this is a per-session setting only.

Describe the solution you'd like
Describe alternatives you've considered
3 solutions i could see:

1. Make the pad type setting a settng exposed in the .bml file
2. Make the setting available through a command-line launch argument
3. For Genesis/Megadrive, default to 6-button pas instead of 3-button (no incompatibility and most games are far more playable in 6-button mode, especially fighting games)

[remutro]

Suggestion number 3 shouldn't be implemented because there are a lot of Mega Drive games that do not work correctly with the 6-button controller. Users would just think there is something wrong with emulating certain games in that configuration if they were not aware there could be an issue. So in the interest of having the largest compatibility, the default should remain the 3 button controller.

Reference: https://segaretro.org/Six_Button_Control_Pad_(Mega_Drive)

[Tartifless]

Yes indeed (not a lot but some), which would be in favor of having this properly in the settings file