Allow specifying URL to compiled Refaster templates

To easily allow sharing / distributing Refaster templates I think it would be nice if the `-XepPatchChecks` would also accept URLs instead of just file system paths. So instead of e.g. `-XepPatchChecks:refaster:/path/to/my/templates.refaster` I would like to be able to use `-XepPatchChecks:refaster:https://example.com/templates.refaster`.