Update commands to work with new JSON format

[apainintheneck]

See Homebrew/brew#16410

The new format exists for formulae right now but not for casks. When the cask work has been merged in, it'd be nice to update the code to handle it. Specifically there should be a command line option to enable the new JSON format which would just set the flag internally and do any other work necessary so that the package loading code mimics the new format. Otherwise, it would skip the new format entirely by removing the HOMEBREW_INTERNAL_JSON_V3 environment variable.