ISPN-4758 Protobuf schema parser should not allow duplicate type definitions

Jira: https://issues.jboss.org/browse/ISPN-4758
 https://issues.jboss.org/browse/ISPN-4761
https://issues.jboss.org/browse/ISPN-4765
I agree, we probably should not assume this placement involving packages. Created https://issues.jboss.org/browse/ISPN-4780