OpenJDK 11: Merging in java.nio.channels.Channels

This is part of merging upstream changes from OpenJDK 11.28. This CL
updates java.lang.nio.channels.Channels.

There are 2 new APIs added for java.nio.channels.Channels:
    static Reader newReader(ReadableByteChannel, Charset);
    static Writer newWriter(WritableByteChannel, Charset);

Tests were merged for the new APIs.

Test: m droid
Test: atest CtsLibcoreTestCases:libcore.java.nio.channels.Channels.{TestName}
Change-Id: Ie84b348c3633754f5e1a390b3d667a9398d255e2
10 files changed