RFR: 8219816: Add IsArray/RemoveArray type traits utilities

[Per Liden]

Add IsArray/RemoveArray to our collection of type traits metaprogramming 
utilities.

This patch only adds the IsArray/RemoveArray utilities and their 
respective tests. A later patch I have in my queue that will actually 
make use of these.

Bug: https://bugs.openjdk.java.net/browse/JDK-8219816
Webrev: http://cr.openjdk.java.net/~pliden/8219816/webrev.0

/Per