Add a script to check Java linkage issues (beam-linkage-check.sh)

https://github.com/apache/beam/pull/10769#issuecomment-584571787

@suztomo can you contribute this script maybe into Beam's build-tools directory so we can improve it a bit for further use?

This is a temporary solution before exclusion rules in Linkage Checker (BEAM-9206) are implemented.