JDK17: nio Buffer classes merge.

This uses the templating through gen_java_nio.py (see comments in file) to
create the Buffer classes from which the new APIs are taken. Tests are taken from the jdk too.

Bug: 240254046
Test: atest {TestName}
Test: m
Change-Id: I36eaf8fcd25bbc7135c9f07d6a662982fea8c4d5
64 files changed