apple/t2: add tiny-dfr option

[reidlabwastaken]

Description of changes

uses mkMerge to separate configuration options in the apple/t2 module, and adds an option to disable tiny-dfr
tiny-dfr is still enabled by default to not cause issues with existing setups that rely on it

Things done

• Tested the changes in your own NixOS Configuration
• Tested the changes end-to-end by using your fork of nixos-hardware and
  importing it via <nixos-hardware> or Flake input

[reidlabwastaken]

if it would make more sense, i could make this another profile instead

[Mic92]

@mergify queue

[mergify]

queue

✅ The pull request has been merged automatically

The pull request has been merged automatically at 6f71da5