EmulatorPkg: Redfish related changes on EmulatorPkg

BZ:
https://bugzilla.tianocore.org/show_bug.cgi?id=3102

- REDFISH_ENABLE definition to control EFI Redfish support
- Add Redfish platform host interface library to
  EmulatorPkg build.
- Set RestExServiceDevicePath PCD value.
- Add Redfish host interface config EFI application
  to EmulatorPkg build.
- Use Redfish DSC/FDF include file.

Signed-off-by: Abner Chang <abner.chang@hpe.com>

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Andrew Fish <afish@apple.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Nickle Wang <nickle.wang@hpe.com>
Cc: Peter O'Hanley <peter.ohanley@hpe.com>
Acked-by: Ray Ni <ray.ni@intel.com>

EmulatorPkg/EmulatorPkg.fdf

@@ -208,6 +208,11 @@ INF  EmulatorPkg/EmuSnpDxe/EmuSnpDxe.inf
 !endif
 !include NetworkPkg/Network.fdf.inc
 
+#
+# EFI Redfish drivers
+#
+!include RedfishPkg/Redfish.fdf.inc
+
 INF FatPkg/EnhancedFatDxe/Fat.inf
 
 !if "XCODE5" not in $(TOOL_CHAIN_TAG)