ModOrganizer 2: Finalize Silent Mode

[sonic2kk]

Finalizes the ModOrganizer 2 Silent Mode implementation. While #1097 implemented the logic to make Silent Mode work, this adds some UX touches to make it easier for users to enable.

• Adds back the "Silent" button on the ModOrganizer 2 Wait Requester, removed a long time ago.
• Adds silent option to MO2MODE dropdown on Game Menu.
• Updates the actions on the Wait Requester to actually respect gui/silent/disabled
  • Newly added "Silent" button will start in silent mode
  • Wait Requester timeout will now default to the selected MO2 mode. Before, we only had two; disabled and gui, so we always defaulted to gui as the sensible choice for the Wait Requester timing out. But now it will actually respect whatever the user selected in disabled. Having said that, the Wait Requester should only appear if MO2MODE is not disabled, so the user won't see it if the mode isn't gui or silent anyway.
• Minor code refactoring

This needs more testing from my side, and once completed this can be merged to fully finalize the MO2 Silent implementation!

Note: I did some work to update the ModOrganizer 2 wiki page, but another pass over it might be good to make sure all the intricacies are documented.