[foreign-memaccess+abi] RFR: API refresh - part two [v7]

[Maurizio Cimadamore]

> After playing a bit more with the new API changes, I realized there were issues with some of the solutions proposed in [1].
> I will add more details in a separate comment, to keep the header of this PR compact.
> 
> [1] - https://git.openjdk.java.net/panama-foreign/pull/576

Maurizio Cimadamore has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains two new commits since the last revision:

 - Some more javadoc fixes on ResourceScope
 - Revert CallOverheadHelper to use shared/confined points
   Fix TestByteBuffer to use implicit scope on some negative tests

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Changes:
  - all: https://git.openjdk.java.net/panama-foreign/pull/591/files
  - new: https://git.openjdk.java.net/panama-foreign/pull/591/files/f17ac3d6..5118cb9e

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=591&range=06
 - incr: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=591&range=05-06

  Stats: 13 lines in 3 files changed: 4 ins; 0 del; 9 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/591.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/591/head:pull/591

PR: https://git.openjdk.java.net/panama-foreign/pull/591