Plugin/CodeQL: Add an integration file (#206)

## Description

Adds a new file (`integration/stuart_codeql.py`) that contains
helper functions for a Stuart-based build environment. The functions
help simplify platform integration.

This is entirely optional and can be used directly or referenced as
an example of how to hook the plugin into a Stuart build.

Other integration related files may be added in this directory in
the future.

- [ ] Impacts functionality?
- [ ] Impacts security?
- [ ] Breaking change?
- [ ] Includes tests?
- [ ] Includes documentation?

## How This Was Tested

Directly used these functions to enable the CodeQL plugin in
several Stuart-based platform builds.

## Integration Instructions

Call the functions in `integration/stuart_codeql.py` if they are
useful to enable the CodeQL plugin in your platform. This file is
optional and only provided for convenience.

Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>

.pytool/Plugin/CodeQL/integration/stuart_codeql.py

@@ -0,0 +1,79 @@
+# @file stuart_codeql.py
+#
+# Exports functions commonly needed for Stuart-based platforms to easily
+# enable CodeQL in their platform build.
+#
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# SPDX-License-Identifier: BSD-2-Clause-Patent
+##
+
+from edk2toolext.environment.uefi_build import UefiBuilder
+from edk2toollib.utility_functions import GetHostInfo
+from argparse import ArgumentParser, Namespace
+from typing import Tuple
+
+
+def add_command_line_option(parser: ArgumentParser) -> None:
+    """Adds the CodeQL command to the platform command line options.
+
+    Args:
+        parser (ArgumentParser): The argument parser used in this build.
+
+    """
+    parser.add_argument(
+        '--codeql',
+        dest='codeql',
+        action='store_true',
+        default=False,
+        help="Optional - Produces CodeQL results from the build. See "
+             "MU_BASECORE/.pytool/Plugin/CodeQL/Readme.md for more info.")
+
+
+def get_scopes(codeql_enabled: bool) -> Tuple[str]:
+    """Returns the active CodeQL scopes for this build.
+
+    Args:
+        codeql_enabled (bool): Whether CodeQL is enabled.
+
+    Returns:
+        Tuple[str]: A tuple of strings containing scopes that enable the
+                    CodeQL plugin.
+    """
+    active_scopes = ()
+
+    if codeql_enabled:
+        if GetHostInfo().os == "Linux":
+            active_scopes += ("codeql-linux-ext-dep",)
+        else:
+            active_scopes += ("codeql-windows-ext-dep",)
+        active_scopes += ("codeql-build", "codeql-analyze")
+
+    return active_scopes
+
+
+def is_codeql_enabled_on_command_line(args: Namespace) -> bool:
+    """Returns whether CodeQL was enabled on the command line.
+
+    Args:
+        args (Namespace): Object holding a string representation of command
+                          line arguments.
+
+    Returns:
+        bool: True if CodeQL is enabled on the command line. Otherwise, false.
+    """
+    return args.codeql
+
+
+def set_audit_only_mode(uefi_builder: UefiBuilder) -> None:
+    """Configures the CodeQL plugin to run in audit only mode.
+
+    Args:
+        uefi_builder (UefiBuilder): The UefiBuilder object for this platform
+                                    build.
+
+    """
+
+    uefi_builder.env.SetValue(
+        "STUART_CODEQL_AUDIT_ONLY",
+        "true",
+        "Platform Defined")