[foreign-jextract] RFR: Improve NIO channel support for buffer views over segments [v3]

[Chris Hegarty]

> Initial prototype changes to use resource scope handles when performing I/O operations with synchronous and asynchronous channels.

Chris Hegarty has updated the pull request incrementally with one additional commit since the last revision:

  Resolve outstanding TODO in MemoryScope spec

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Changes:
  - all: https://git.openjdk.java.net/panama-foreign/pull/512/files
  - new: https://git.openjdk.java.net/panama-foreign/pull/512/files/a88ad97a..d8d29d3a

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=512&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=512&range=01-02

  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/512.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/512/head:pull/512

PR: https://git.openjdk.java.net/panama-foreign/pull/512