OvmfPkg: Add QemuFwCfgLib library class and implementation

QEMU's Firmware Configuration interface gives the firmware
access to various types of information.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13383 6f19259b-4bc3-4df7-8a09-765794883524
11 files changed