Create Google mock for ReadOnlyVariable2 (#579)

## Description

Create Google mock for ReadOnlyVariable2
Created a new PR for cleaner single-commit (also this one works)
Old PR: #530

- [ ] Impacts functionality?
- **Functionality** - Does the change ultimately impact how firmware
functions?
- Examples: Add a new library, publish a new PPI, update an algorithm,
...
- [ ] Impacts security?
- **Security** - Does the change have a direct security impact on an
application,
    flow, or firmware?
  - Examples: Crypto algorithm change, buffer overflow fix, parameter
    validation improvement, ...
- [ ] Breaking change?
- **Breaking change** - Will anyone consuming this change experience a
break
    in build or boot behavior?
- Examples: Add a new library class, move a module to a different repo,
call
    a function in a new library class in a pre-existing module, ...
- [ ] Includes tests?
  - **Tests** - Does the change include any explicit test code?
  - Examples: Unit tests, integration tests, robot tests, ...
- [ ] Includes documentation?
- **Documentation** - Does the change contain explicit documentation
additions
    outside direct code modifications (and comments)?
- Examples: Update readme file, add feature readme file, link to
documentation
    on an a separate Web page, ...

## How This Was Tested

Tested with ConfigKnobShimLib GoogleTest

## Integration Instructions

N/A

MdePkg/Test/Mock/Include/GoogleTest/Ppi/MockReadOnlyVariable2.h

@@ -0,0 +1,49 @@
+/** @file MockReadOnlyVariable2.h
+  This file declares a mock of Read-only Variable Service2 PPI.
+
+  This PPI permits read-only access to the UEFI variable store during the PEI phase.
+
+  Copyright (c) Microsoft Corporation.
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#ifndef MOCK_PEI_READ_ONLY_VARIABLE2_PPI_H
+#define MOCK_PEI_READ_ONLY_VARIABLE2_PPI_H
+
+#include <Library/GoogleTestLib.h>
+#include <Library/FunctionMockLib.h>
+extern "C" {
+#include <Uefi.h>
+#include <Pi/PiPeiCis.h>
+#include <Ppi/ReadOnlyVariable2.h>
+}
+
+struct MockReadOnlyVariable2 {
+  MOCK_INTERFACE_DECLARATION (MockReadOnlyVariable2);
+
+  MOCK_FUNCTION_DECLARATION (
+    EFI_STATUS,
+    GetVariable,
+    (IN CONST  EFI_PEI_READ_ONLY_VARIABLE2_PPI  *This,
+     IN CONST  CHAR16                           *VariableName,
+     IN CONST  EFI_GUID                         *VariableGuid,
+     OUT       UINT32                           *Attributes,
+     IN OUT    UINTN                            *DataSize,
+     OUT       VOID                             *Data OPTIONAL)
+    );
+
+  MOCK_FUNCTION_DECLARATION (
+    EFI_STATUS,
+    NextVariableName,
+    (IN CONST  EFI_PEI_READ_ONLY_VARIABLE2_PPI *This,
+     IN OUT    UINTN                           *VariableNameSize,
+     IN OUT    CHAR16                          *VariableName,
+     IN OUT    EFI_GUID                        *VariableGuid)
+    );
+};
+
+extern "C" {
+extern EFI_PEI_READ_ONLY_VARIABLE2_PPI  *PpiReadOnlyVariableServices;
+}
+
+#endif

MdePkg/Test/Mock/Library/GoogleTest/Ppi/MockReadOnlyVariable2.cpp

@@ -0,0 +1,23 @@
+/** @file MockReadOnlyVariable2.cpp
+  Google Test mock for ReadOnlyVariable2
+
+  Copyright (c) Microsoft Corporation.
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include <GoogleTest/Ppi/MockReadOnlyVariable2.h>
+
+MOCK_INTERFACE_DEFINITION (MockReadOnlyVariable2);
+MOCK_FUNCTION_DEFINITION (MockReadOnlyVariable2, GetVariable, 6, EFIAPI);
+MOCK_FUNCTION_DEFINITION (MockReadOnlyVariable2, NextVariableName, 4, EFIAPI);
+
+// Normally PpiVariableServices is "found"
+// This will be defined INSIDE the test, with its definition pointing to the mock function GetVariable
+EFI_PEI_READ_ONLY_VARIABLE2_PPI  PeiReadOnlyVariablePpi = {
+  GetVariable,      // EFI_PEI_GET_VARIABLE2
+  NextVariableName  // EFI_PEI_GET_NEXT_VARIABLE_NAME2
+};
+
+extern "C" {
+EFI_PEI_READ_ONLY_VARIABLE2_PPI  *PpiReadOnlyVariableServices = &PeiReadOnlyVariablePpi;
+}