Fix JNIVector garbage collection, check if JVM destroyed

[mkitti]

Fixes:

1. Explicitly set own = false with unsafe_wrap since Java should free the array, not Julia
2. Make sure the JVM has not been destroyed before we to call Release*

cc: @ahnlabb

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (master@96353a4). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #163   +/-   ##
=========================================
  Coverage          ?   64.43%           
=========================================
  Files             ?       10           
  Lines             ?      984           
  Branches          ?        0           
=========================================
  Hits              ?      634           
  Misses            ?      350           
  Partials          ?        0           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 96353a4...5cbc6c3. Read the comment docs.

[mkitti]

The JNI module should be fixed so that one can just pass the array rather than explicitly having to extract the pointer via pointer.