[foreign-jextract] RFR: 8263018: Improve API for lifecycle of native resources

[Maurizio Cimadamore]

This contains the jextract changes required to support the new changes to the foreign memory access API.

The main change is that now NativeScope is co-generated by jextract (although, moving forward, I'm not sure how much value it adds, but that's for another day).

I had to fix the extracted libclang in few places (probably better to re-generate this code once this is pushed).

Tests needed changes to fix imports so that they pick up the generated NativeScope class.

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Commit messages:
 - Merge branch 'foreign-memaccess+abi' into jextract+resourceScope
 - 8263018: Improve API for lifecycle of native resources
 - Merge branch 'foreign-jextract' into jextract+resourceScope
 - Add overloads accepting ResourceScope parameter
 - Merge branch 'resourceScope' into jextract+resourceScope
 - Add ResourceScope overloads in CLinker
 - All tests pass
 - Merge branch 'resourceScope' into jextract+resourceScope
 - Fix javadoc of SegmentAllocator
 - Address rest of review comments from Paul
 - ... and 88 more: https://git.openjdk.java.net/panama-foreign/compare/b5b4cc76...b5f38d93

Changes: https://git.openjdk.java.net/panama-foreign/pull/474/files
 Webrev: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=474&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8263018
  Stats: 7344 lines in 119 files changed: 3355 ins; 2829 del; 1160 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/474.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/474/head:pull/474

PR: https://git.openjdk.java.net/panama-foreign/pull/474