[macOS] Fail builds on errors during the image generation (#1756)

* set -e and fix all the scripts

* add source utils to finalize_vm script

* change xcode version in postbuild script

* fix for softwareupdates and for xcode version

images/macos/provision/core/php.sh

@@ -1,5 +1,4 @@
-#!/bin/sh
-set -e
+#!/bin/bash -e -o pipefail
 
 echo Installing PHP
 brew install php