RFR: 8304265: Implementation of Foreign Function and Memory API (Third Preview) [v20]

[Per Minborg]

> API changes for the FFM API (third preview)
> 
> Specdiff:
> https://cr.openjdk.org/~pminborg/panama/21/v1/specdiff/overview-summary.html
> 
> Javadoc:
> https://cr.openjdk.org/~pminborg/panama/21/v1/javadoc/java.base/module-summary.html

Per Minborg has updated the pull request incrementally with two additional commits since the last revision:

 - 8305369: Issues in zero-length memory segment javadoc section
 - 8305087: MemoryLayout API checks should be more eager

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/13079/files
  - new: https://git.openjdk.org/jdk/pull/13079/files/0ee65ac1..c1999447

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13079&range=19
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13079&range=18-19

  Stats: 340 lines in 21 files changed: 98 ins; 184 del; 58 mod
  Patch: https://git.openjdk.org/jdk/pull/13079.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13079/head:pull/13079

PR: https://git.openjdk.org/jdk/pull/13079