RFR: 8282191: Implementation of Foreign Function & Memory API (Preview) [v30]

[Maurizio Cimadamore]

> This PR contains the API and implementation changes for JEP-424 [1]. A more detailed description of such changes, to avoid repetitions during the review process, is included as a separate comment.
> 
> [1] - https://openjdk.java.net/jeps/424

Maurizio Cimadamore has updated the pull request incrementally with four additional commits since the last revision:

 - Add ValueLayout changes
 - Tweak support for array element var handle
 - Add @see
 - Initial push

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7888/files
  - new: https://git.openjdk.java.net/jdk/pull/7888/files/8637379e..2e3d57a8

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7888&range=29
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7888&range=28-29

  Stats: 129 lines in 4 files changed: 97 ins; 25 del; 7 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7888.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7888/head:pull/7888

PR: https://git.openjdk.java.net/jdk/pull/7888