suppress_deprecation: handle use for class without process method
suppress_deprecation: handle use for class without process method

The decorator cannot be used on every class. It's expected a class
has the process method. Instead of confusing simple crash,
raise an exception with a meaningful message when decorator is used
on class without the process method.

leapp-to/prototype,leapp-to/prototype,leapp-to/prototype,leapp-to/prototype