Installer, bootstrapper, and executable signing for Windows (#4406)

* Added a codesigning script to pre and post build steps in the Windows installer CD job

* Changed `windows_installer` job name to `installer_vs2019`

* Added `installer-nightly` tag for `installer_vs2019`

* Updated `build_config.json` to use an envvar for the installer url and bucket

Signed-off-by: Mike Chang <changml@amazon.com>

cmake/Platform/Windows/PackagingPreBuild.cmake

@@ -0,0 +1,37 @@
+#
+# Copyright (c) Contributors to the Open 3D Engine Project.
+# For complete copyright and license terms please see the LICENSE at the root of this distribution.
+#
+# SPDX-License-Identifier: Apache-2.0 OR MIT
+#
+#
+
+file(REAL_PATH "${CPACK_SOURCE_DIR}/.." _root_path)
+set(_cpack_wix_out_dir ${CPACK_TOPLEVEL_DIRECTORY})
+file(TO_NATIVE_PATH "${_root_path}/scripts/signer/Platform/Windows/signer.ps1" _sign_script)
+
+set(_signing_command
+    psexec.exe
+    -accepteula 
+    -nobanner 
+    -s
+    powershell.exe
+    -NoLogo
+    -ExecutionPolicy Bypass 
+    -File ${_sign_script}
+)
+
+message(STATUS "Signing executable files in ${_cpack_wix_out_dir}")
+execute_process(
+    COMMAND ${_signing_command} -exePath ${_cpack_wix_out_dir}
+    RESULT_VARIABLE _signing_result
+    ERROR_VARIABLE _signing_errors
+    OUTPUT_VARIABLE _signing_output
+    ECHO_OUTPUT_VARIABLE
+)
+
+if(NOT ${_signing_result} EQUAL 0)
+    message(FATAL_ERROR "An error occurred during signing executable files.  ${_signing_errors}")
+endif()
+
+message(STATUS "Signing exes complete!")