OvmfPkg: QemuBootOrderLib: featurize PCI-like device path translation

OvmfPkg: QemuBootOrderLib: featurize PCI-like device path translation

In preparation for adding OpenFirmware-to-UEFI translation for "MMIO-like"
OFW device path fragments, let's turn the currently exclusive "PCI-like"
translation into "just one" of the possible translations.

- Rename TranslateOfwNodes() to TranslatePciOfwNodes(), because it is
  tightly coupled to "PCI-like" translations.

- Rename REQUIRED_OFW_NODES to REQUIRED_PCI_OFW_NODES, because this macro
  is specific to TranslatePciOfwNodes().

- Introduce a new wrapper function under the original TranslateOfwNodes()
  name. This function is supposed to try translations in some order until
  a specific translation returns a status different from
  RETURN_UNSUPPORTED.

- Introduce a new Feature PCD that controls whether PCI translation is
  attempted at all.

- The boot option "survival policy" in BootOrderComplete() must take into
  account if the user was able to select PCI-like boot options. If the
  user had no such possibility (because the Feature PCD was off for
  PCI-like translation), then we ought to keep any such unselected boot
  options.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16571 6f19259b-4bc3-4df7-8a09-765794883524