test(osarch): add unit test for osarch

Author: noelmcloughlin

test/integration/default/controls/config_spec.rb

@@ -15,6 +15,7 @@
     its('content') { should include '"pkg": {"name": "' }
     its('content') { should include '"service": {"name": "' }
     its('content') { should include '"tofs": {"files_switch": ["any/path/can/be/used/here", "id", "roles", "osfinger", "os", "os_family"], "source_files": {"template-config-file-file-managed": ["example.tmpl.jinja"]}' }
+    its('content') { should include '"arch": "amd64"' }
     its('content') { should include '"winner": "pillar"}' }
     its('content') { should include 'winner of the merge: pillar' }
   end