OvmfPkg: Enable APs to accept memory for TDVF

OvmfPkg: Enable APs to accept memory for TDVF

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4172

TDVF APs once did nothing but spin around to wait for the Wakeup command.
This patch enables APs to handle the AcceptPages command. Once APs find
the AcceptPages command, it set its stack and jump to the function of
ApAcceptMemoryResourceRange (which will be introduced in the following
patch).

Cc: Erdem Aktas <erdemaktas@google.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Min Xu <min.m.xu@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>