RFR: 8266851: Implement JEP 403: Strongly Encapsulate JDK Internals

[Mark Reinhold]

Please review this implementation of JEP 403 (https://openjdk.java.net/jeps/403).
Alan Bateman is the original author of almost all of it.  Passes tiers 1-3 on 
{linux,macos,windows}-x64 and {linux,macos}-aarch64.

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Commit messages:
 - 8266851: Implement JEP 403: Strongly Encapsulate JDK Internals

Changes: https://git.openjdk.java.net/jdk/pull/4015/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4015&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8266851
  Stats: 2811 lines in 16 files changed: 0 ins; 2782 del; 29 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4015.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4015/head:pull/4015

PR: https://git.openjdk.java.net/jdk/pull/4015