StandaloneMmPkg/Core: permit encapsulated firmware volumes

StandaloneMmPkg/Core: permit encapsulated firmware volumes

Standalone MM requires 4 KB section alignment for all images, so that
strict permissions can be applied. Unfortunately, this results in a
lot of wasted space, which is usually costly in the secure world
environment that standalone MM is expected to operate in.

So let's permit the standalone MM drivers (but not the core) to be
delivered in a compressed firmware volume.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: "Yao, Jiewen" <jiewen.yao@intel.com>
Reviewed-by: Achin Gupta <achin.gupta@arm.com>