BaseTools/Plugin/CodeQL: Add CodeQL build plugin

Adds a CodeQL plugin that supports CodeQL in the build system.

1. CodeQlBuildPlugin - Generates a CodeQL database for a given build.
2. CodeQlAnalyzePlugin - Analyzes a CodeQL database and interprets
   results.
3. External dependencies - Assist with downloading the CodeQL CLI and
   making it available to the CodeQL plugins.
4. CodeQlQueries.qls - A C/C++ CodeQL query set run against the code.
5. Readme.md - A comprehensive readme file to help:
   - Platform integrators understand how to configure the plugin
   - Developers understand how to modify the plugin
   - Users understand how to use the plugin

Read Readme.md for additional details.

Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Rebecca Cran <rebecca@bsdio.com>
Cc: Sean Brogan <sean.brogan@microsoft.com>
Cc: Yuwei Chen <yuwei.chen@intel.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Reviewed-by: Yuwei Chen <yuwei.chen@intel.com>
Reviewed-by: Sean Brogan <sean.brogan@microsoft.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Michael D Kinney <michael.d.kinney@intel.com>

BaseTools/Plugin/CodeQL/codeqlcli_ext_dep.yaml

@@ -0,0 +1,26 @@
+## @file codeqlcli_ext_dep.yaml
+#
+# Downloads the CodeQL Command-Line Interface (CLI) application that support Linux, Windows, and Mac OS X.
+#
+# This download is very large but conveniently provides support for all operating systems. Use it if you
+# need CodeQL CLI support without concern for the host operating system.
+#
+# In an environment where a platform might build in different operating systems, it is recommended to set
+# the scope for the appropriate CodeQL external dependency based on the host operating system being used.
+#
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# SPDX-License-Identifier: BSD-2-Clause-Patent
+##
+
+{
+  "scope": "codeql-ext-dep",
+  "type": "web",
+  "name": "codeql_cli",
+  "source": "https://github.com/github/codeql-cli-binaries/releases/download/v2.12.4/codeql.zip",
+  "version": "2.12.4",
+  "sha256": "f682f1155d627ad97f10b1bcad97f682011986717bd3823e9cf831ed83ac96e7",
+  "compression_type": "zip",
+  "internal_path": "/codeql/",
+  "flags": ["set_shell_var", ],
+  "var_name": "STUART_CODEQL_PATH"
+}