MsvmPkg: Add virtio-blk over PCI support (ported from EDK2 OvmfPkg)

[jstarks]

Port the virtio-blk-over-PCI driver stack from EDK2 OvmfPkg into MsvmPkg for both X64 and AARCH64.

Modules added (drivers):

• MsvmPkg/VirtioBlkDxe (OvmfPkg/VirtioBlkDxe)
• MsvmPkg/Virtio10Dxe (OvmfPkg/Virtio10Dxe, modern 1.0 PCI transport)
• MsvmPkg/VirtioPciDeviceDxe (OvmfPkg/VirtioPciDeviceDxe, legacy transport)

Libraries added:

• MsvmPkg/Library/VirtioLib (OvmfPkg/Library/VirtioLib)
• MsvmPkg/Library/BasePciCapLib (OvmfPkg/Library/BasePciCapLib)
• MsvmPkg/Library/UefiPciCapPciIoLib (OvmfPkg/Library/UefiPciCapPciIoLib)

Headers added under MsvmPkg/Include:
IndustryStandard/{Virtio,Virtio095,Virtio10,VirtioBlk}.h,
Protocol/VirtioDevice.h, Library/{VirtioLib,PciCapLib,PciCapPciIoLib}.h

Wiring:

• MsvmPkg.dec: define gVirtioDeviceProtocolGuid (value preserved from OvmfPkg)
• MsvmPkgX64.dsc / MsvmPkgAARCH64.dsc: add VirtioLib/PciCapLib/PciCapPciIoLib library classes and the three driver components
• MsvmPkgX64.fdf / MsvmPkgAARCH64.fdf: add the three drivers to the DXE FV

The only change to the upstream sources is retargeting each INF's [Packages] from OvmfPkg/OvmfPkg.dec to MsvmPkg/MsvmPkg.dec; the .c/.h files are verbatim.

Source provenance:
Repository: https://github.com/tianocore/edk2
Tag: edk2-stable202511
Commit: 46548b1adac82211d8d11da12dd914f41e7aa775

[chris-oo]

This is fine with me, but I did have a question on how we want to handle this code in the future. Is this commit message equivalent or do others think we should have some kind of provenance in the repo for the drivers?

Additionally, I think with the way these drivers bind they will be no-ops if we don't expose any virtio devices, right? Or is there another way we can make sure that these drivers don't load when they're not expected to?

I'd also like Oliver/someone on sean's team to comment as well.