BaseTools/Capsule: Supports multiple payloads and drivers in capsule

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1834

1)Add arguments "--embedded-driver" to support embedded driver
in command line.
2)Add arguments "--update-image-index" to identify ImageIndex
within the device in command line.
3)Add arguments "-j JSONFILE" to support multiple payloads and
embedded drivers with JSON file.

The update is in a backwards compatible manner, so all command
line options to support single payload are still supported. But
all the options associated with multiple payloads should be
provided in a JSON file.

Cc: Bob Feng <bob.c.feng@intel.com>
Signed-off-by: Eric Jin <eric.jin@intel.com>
Reviewed-by: Bob Feng <bob.c.feng@intel.com>

BaseTools/Source/Python/Common/Uefi/Capsule/FmpAuthHeader.py

@@ -2,7 +2,7 @@
 # Module that encodes and decodes a EFI_FIRMWARE_IMAGE_AUTHENTICATION with
 # certificate data and payload data.
 #
-# Copyright (c) 2018, Intel Corporation. All rights reserved.<BR>
+# Copyright (c) 2018 - 2019, Intel Corporation. All rights reserved.<BR>
 # SPDX-License-Identifier: BSD-2-Clause-Patent
 #
 
@@ -166,6 +166,18 @@ class FmpAuthHeaderClass (object):
         self._Valid           = True
         return self.Payload
 
+    def IsSigned (self, Buffer):
+        if len (Buffer) < self._StructSize:
+            return False
+        (MonotonicCount, dwLength, wRevision, wCertificateType, CertType) = \
+            struct.unpack (
+                     self._StructFormat,
+                     Buffer[0:self._StructSize]
+                     )
+        if CertType != self._EFI_CERT_TYPE_PKCS7_GUID.bytes_le:
+            return False
+        return True
+
     def DumpInfo (self):
         if not self._Valid:
             raise ValueError