[vectorIntrinsics] RFR: 8283598: [vectorapi] Add new vector operation for compress bits [v2]

[Smita Kamath]

> Hi,
> 
> I've added support for new vector operations for compressing bits of integral vector types(Byte/Short/Integer/Long).
> The implementation is based on Compress or Generalized Extract mentioned in Hackers Delight by Henry S. Warren, Jr.
> The implementation does the following: given a mask and the number to be compressed, the bits of the number corresponding to the set mask bit are selected and compressed. 
> 
> Currently, this PR addresses only Java changes for compress bits operation. I've also updated the test framework.
> Do review and share feedback.

Smita Kamath has updated the pull request incrementally with one additional commit since the last revision:

  1) Removed compress bits implementation for byte and short
  2) Added expand bits operation for int and long 3) Addressed review comments about code style 4) updated tests

-------------

Changes:
  - all: https://git.openjdk.java.net/panama-vector/pull/184/files
  - new: https://git.openjdk.java.net/panama-vector/pull/184/files/ad5be3c0..054e95cf

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=184&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=184&range=00-01

  Stats: 2985 lines in 83 files changed: 1605 ins; 1164 del; 216 mod
  Patch: https://git.openjdk.java.net/panama-vector/pull/184.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-vector pull/184/head:pull/184

PR: https://git.openjdk.java.net/panama-vector/pull/184