OvmfPkg/Library: Create base HardwareInfoLib for PCI Host Bridges

OvmfPkg/Library: Create base HardwareInfoLib for PCI Host Bridges

Create the Hardware Info library base together with the specifics to
describe PCI Host Bridges.

The Hardware Info library is intended to be used for disclosing
non-discoverable hardware information from the host to the guest in
Ovmf platforms. Core functionality will provide the possibility to
parse information from a generic BLOB into runtime structures. The
library is conceived in a generic way so that further hardware
elements can also be described using it. For such purpose the length
of the BLOB is not restricted but instead regarded as a sequence of
header-info elements that allow the parsing during runtime. The first
type of hardware defined will be PCI host bridges, providing the
possibility to define multiple and specify the resources each of them
can use. This enables the guest firmware to configure PCI resources
properly. Having the size of each individual element favors the reuse
of a single interface to convey descriptions of an arbitrary number
of heterogenous hardware elements. Furthermore, flexible access
mechanisms coupled with the size will grant the possibility of
interpreting them in a single run.

Define the base types of the generic Hardware Info library to parse
heterogeneous data. Also provide the specific changes to support
PCI host bridges as the first hardware type supported by the
library.
Additionally, define the HOST_BRIDGE_INFO structure to describe PCI
host bridges along with the functionality to parse such information
into proper structures used by the PCI driver in a centralized manner
and taking care of versioning.

As an example and motivation, the library will be used to define
multiple PCI host bridges for complex platforms that require it.
The first means of transportation that will be used is going to be
fw-cfg, over which a stream of bytes will be transferred and later
parsed by the hardware info library. Accordingly, the PCI driver
will make use of these host bridges definitions to populate the
list of Root Bridges and proceed with the configuration and discovery
of underlying hardware components.

As mentioned before, the binary data to be parsed by the Hardware
Info library should be organized as a sequence of Header-element
pairs in which the header describes the type and size of the associated
element that comes right after it. As an illustration, to provide
inforation of 3 host bridges the data, conceptually, would look
like this:

Header PCI Host Bridge (type and size) # 1
PCI Host Bridge info # 1
Header PCI Host Bridge (type and size) # 2
PCI Host Bridge info # 2
Header PCI Host Bridge (type and size) # 3
PCI Host Bridge info # 3

Cc: Alexander Graf <graf@amazon.de>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Nicolas Ojeda Leon <ncoleon@amazon.com>