Only download archive if necessary [macos]

[noelmcloughlin]

It is wasteful downloading fresh archive if cached one already exists (with valid checksum).

This PR implements the improvement.

[noelmcloughlin]

Great question @vschumaker Yes we have to check the hashsum - I changed onchanges to require to ensure its checked.

mysql-macos-check-{{ product }}-archive-hash:
   module.run:
     - name: file.check_hash
     - path: {{ dl.tmpdir }}/{{ archivefile }}
     - file_hash: {{ data.sum }}
     - require:               <===== here
       - cmd: mysql-macos-download-{{ product }}-archive