OvmfPkg: Update PlatformPei to support Tdx guest

RFC: https://bugzilla.tianocore.org/show_bug.cgi?id=3429

OvmfPkg/PlatformPei is updated to support Tdx guest. There are below
major changes.
 - Set Tdx related PCDs
 - Publish Tdx RamRegions

In this patch there is another new function BuildPlatformInfoHob ().
This function builds EFI_HOB_PLATFORM_INFO which contains the
HostBridgeDevId. The hob is built in both Td guest and Non-Td guest.

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Min Xu <min.m.xu@intel.com>

OvmfPkg/OvmfPkg.dec

@@ -133,6 +133,7 @@
   gGrubFileGuid                         = {0xb5ae312c, 0xbc8a, 0x43b1, {0x9c, 0x62, 0xeb, 0xb8, 0x26, 0xdd, 0x5d, 0x07}}
   gConfidentialComputingSecretGuid      = {0xadf956ad, 0xe98c, 0x484c, {0xae, 0x11, 0xb5, 0x1c, 0x7d, 0x33, 0x64, 0x47}}
   gConfidentialComputingSevSnpBlobGuid  = {0x067b1f5f, 0xcf26, 0x44c5, {0x85, 0x54, 0x93, 0xd7, 0x77, 0x91, 0x2d, 0x42}}
+  gUefiOvmfPkgPlatformInfoGuid          = {0xdec9b486, 0x1f16, 0x47c7, {0x8f, 0x68, 0xdf, 0x1a, 0x41, 0x88, 0x8b, 0xa5}}
 
 [Ppis]
   # PPI whose presence in the PPI database signals that the TPM base address