RFR: 8304265: Implementation of Foreign Function and Memory API (Third Preview) [v21]

[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 with a new target base due to a merge or a rebase. The pull request now contains 36 commits:

 - Merge branch 'master' into PR_21_V2
 - 8305369: Issues in zero-length memory segment javadoc section
 - 8305087: MemoryLayout API checks should be more eager
 - Merge master
 - Improve code snipet
 - Update JEP number and name
 - Update src/java.base/share/classes/java/lang/foreign/MemorySegment.java
   
   Co-authored-by: Maurizio Cimadamore <54672762+mcimadamore at users.noreply.github.com>
 - Update src/java.base/share/classes/java/lang/foreign/MemorySegment.java
   
   Co-authored-by: Maurizio Cimadamore <54672762+mcimadamore at users.noreply.github.com>
 - Cleanup finality
 - Merge pull request #1 from JornVernee/Fix_ULE
   
   Fix ULE when intializing LibFallback
 - ... and 26 more: https://git.openjdk.org/jdk/compare/d8af7a60...5de90878

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

Changes: https://git.openjdk.org/jdk/pull/13079/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13079&range=20
  Stats: 13418 lines in 270 files changed: 5099 ins; 6182 del; 2137 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