[Java/Python] Add pyarrow.{Array,Field}.from_jvm / jvm_buffer

[asfimport]

As a first iteration of the Java->Python in-memory vector sharing, add a minimal set of functions to access primitive arrays from Java in Python.

Reporter: Uwe Korn / @xhochy
Assignee: Uwe Korn / @xhochy

Related issues:

• [Java/Python] in-process vector sharing from Java to Python (is a child of)

PRs and other links:

• GitHub Pull Request apache/arrow#2062

_{Note: This issue was originally created as ARROW-2608. Please see the migration documentation for further details.}

[asfimport]

Uwe Korn / @xhochy:
Issue resolved by pull request 2062
#2062