This resolves the general set of compatibility issues with macOS 12
software updater, which requires T2 mac models to have T2 SB models.

This variable is derived from `SecureBootModel` specified in the config
(e.g. j137 becomes J137AP) and is used by macOS 12 during updates
and installations. Setting this variable allows to use macOS 12
with T2 board identifiers, e.g. j137.

closes acidanthera/bugtracker#1783

To allow kb input to reliably reach ConIn GUI apps (e.g. Windows BitLocker) even when an AppleEvent key handler (e.g. CrScreenshotDxe.efi) is active

Docs: Sync with https://github.com/acidanthera/OpenCorePkg/commit/24214b8a0c034addd814ae321f905a30a903f5c0

https://github.com/acidanthera/bugtracker/issues/1703