pkg/machine/ocipull: add default policy.json file

So that this file can be inculded in our windows/macos packages and also
by other packagers.
Right now the default policy is allow everything but we plan to add
signing in the future.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

pkg/machine/ocipull/policy.json

@@ -0,0 +1,7 @@
+{
+    "default": [
+        {
+            "type": "insecureAcceptAnything"
+        }
+    ]
+}