Bundle jar for xtable for ease of use with various engines

[vinothchandar]

Context:

To use XTable right now, the users are expected to build the project [1] and don't have an easy way to include a xtable jar here.

Users need a simple, reliable way to include xtable inside their existing engines/runtimes, to get cross format/catalog interop.

Proposal/Ask:

Publish xtable-bundle jars along with the next release, that can be easily used inside engine runtimes. e.g --jars <xtable-bundle.jar> for a spark-submit. Recommend designing the bundle jars to be as thin as possible following two principles.

1. Use the engine or the table format's own runtime/bundle jars as much as possible. Don't package a really large bundle pulling all possible transitive dependency. (Hudi for e.g explicitly whitelists what goes into the bundle jar)
2. Shade dependencies used by the xtable code itself (which I expect to be small-ish atm)