Add platform specific codesign script and modifications for Linux and Windows installer packaging (#5893)

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

cmake/Platform/Linux/PackagingCodeSign_linux.cmake

@@ -0,0 +1,33 @@
+#
+# 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
+#
+#
+
+function(ly_sign_binaries in_path)
+    message(STATUS "Executing package signing...")
+    file(REAL_PATH "${CPACK_SOURCE_DIR}/.." _root_path)
+    unset(_signing_command)
+
+    cmake_path(SET _sign_script "${_root_path}/scripts/signer/Platform/Linux/signer.sh")
+
+    list(APPEND _signing_command
+        ${_sign_script}
+    )
+    message(STATUS "Signing package files in ${in_path}")
+    execute_process(
+        COMMAND ${_signing_command} ${in_path}
+        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 files.  ${_signing_errors}")
+    else()
+        message(STATUS "Signing complete!")
+    endif()
+endfunction()