RFR: 8264774: Implementation of Foreign Function and Memory API (Incubator) [v6]

[Maurizio Cimadamore]

> This PR contains the API and implementation changes for JEP-412 [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/412

Maurizio Cimadamore has updated the pull request incrementally with one additional commit since the last revision:

  * Add @CS to interface methods in the Foreign API
  * Beef up test for methd handles and restricted methods

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3699/files
  - new: https://git.openjdk.java.net/jdk/pull/3699/files/f27db3f3..75474a1f

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3699&range=05
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3699&range=04-05

  Stats: 306 lines in 8 files changed: 306 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3699.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3699/head:pull/3699

PR: https://git.openjdk.java.net/jdk/pull/3699