[vector] Vector API is integerated

[Paul Sandoz]

Hi,

The Vector API is now integrated, as an incubating module, into the main JDK repository. 

A multi-year multi-org multi-person effort has reached the end of the beginning. Much respect to all involved.

There is more to do :-)

Short term, before ramp down phase 1 of JDK 16 [1], we need to sweep up some trailing issues. Jie, Ningsheng, thanks for waiting, feel free to create PRs for x86 AVX-512 and ARM SVE issues against the main repo.

Longer term there are a few focus areas such as masking, loops with masks, the important connection with Project Valhalla, x86 stubs for transcendental functions, and the ongoing focus on code generation and performance. Contributions of data-parallel algorithms as JMH benchmarks are especially welcome. 

Paul.

[1] https://openjdk.java.net/projects/jdk/16/