[Gandiva] Generate object ids for modules

Generate object identifiers for Projector and Filter, so that we can test the external layer to C++ if the identifier is the same to ensure that caching is not broken.

Introduce JNI api to query for the same.

However this is not of high priority since we have tests in the core gandiva layer for the same.

Current tests depend on time but it is causing spurious failures.

Reporter: Praveen Kumar / @praveenbingo

Note: This issue was originally created as ARROW-4371. Please see the migration documentation for further details.