[Java] Remove split packages in arrow-memory-core and arrow-vectors

The java package (org.apache.arrow.util) is provided in two different artifacts

arrow-memory-core: (Link to GitHub)
arrow-vectors: (Link to GitHub) This is causing trouble when using OSGI dependency management. After converting the maven artifacts to OSGI bundles the package is available via two chains (which is not allowed).

Additionally, the Java 9+ module system (JPMS) does not allow for split packages either. See here.

This was mentioned in the mailing list.

Possible solutions are:
Renaming the packages to org.apache.arrow.vector.util and org.apache.arrow.memory.util
Moving the classes from vector to memory-core

Reporter: Benjamin Wilhelm

_{Note: This issue was originally created as ARROW-10333. Please see the migration documentation for further details.}

apache / arrow