CryptoPkg: Add Null instance of the BaseCryptLib class

https://bugzilla.tianocore.org/show_bug.cgi?id=2257

Add a Null instance of the BaseCryptLib class.  This lib instance
can be used as a template for new implementations of the BaseCryptLib
class and can also be used to reduce CI build times for build
checks that depend on the BaseCryptLib class.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Xiaoyu Lu <xiaoyux.lu@intel.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Jian J Wang <jian.j.wang@intel.com>

CryptoPkg/Library/BaseCryptLibNull/Pk/CryptPkcs7SignNull.c

@@ -0,0 +1,54 @@
+/** @file
+  PKCS#7 SignedData Sign Wrapper Implementation which does not provide real
+  capabilities.
+
+Copyright (c) 2012, Intel Corporation. All rights reserved.<BR>
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include "InternalCryptLib.h"
+
+/**
+  Creates a PKCS#7 signedData as described in "PKCS #7: Cryptographic Message
+  Syntax Standard, version 1.5". This interface is only intended to be used for
+  application to perform PKCS#7 functionality validation.
+
+  Return FALSE to indicate this interface is not supported.
+
+  @param[in]  PrivateKey       Pointer to the PEM-formatted private key data for
+                               data signing.
+  @param[in]  PrivateKeySize   Size of the PEM private key data in bytes.
+  @param[in]  KeyPassword      NULL-terminated passphrase used for encrypted PEM
+                               key data.
+  @param[in]  InData           Pointer to the content to be signed.
+  @param[in]  InDataSize       Size of InData in bytes.
+  @param[in]  SignCert         Pointer to signer's DER-encoded certificate to sign with.
+  @param[in]  OtherCerts       Pointer to an optional additional set of certificates to
+                               include in the PKCS#7 signedData (e.g. any intermediate
+                               CAs in the chain).
+  @param[out] SignedData       Pointer to output PKCS#7 signedData. It's caller's
+                               responsibility to free the buffer with FreePool().
+  @param[out] SignedDataSize   Size of SignedData in bytes.
+
+  @retval FALSE  This interface is not supported.
+
+**/
+BOOLEAN
+EFIAPI
+Pkcs7Sign (
+  IN   CONST UINT8  *PrivateKey,
+  IN   UINTN        PrivateKeySize,
+  IN   CONST UINT8  *KeyPassword,
+  IN   UINT8        *InData,
+  IN   UINTN        InDataSize,
+  IN   UINT8        *SignCert,
+  IN   UINT8        *OtherCerts      OPTIONAL,
+  OUT  UINT8        **SignedData,
+  OUT  UINTN        *SignedDataSize
+  )
+{
+  ASSERT (FALSE);
+  return FALSE;
+}
+