RFR: Merge jdk8u:master

[Andrew John Hughes]

Merge jdk8u382-b04

GHA builds will not work until [JDK-8293107](https://bugs.openjdk.org/browse/JDK-8293107) is merged in 8u462-b01

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

Commit messages:
 - Merge jdk8u382-b04
 - 8241311: Move some charset mapping tests from closed to open
 - 8186801: Add regression test to test mapping based charsets (generated at build time)

The merge commit only contains trivial merges, so no merge-specific webrevs have been generated.

Changes: https://git.openjdk.org/shenandoah-jdk8u/pull/50/files
  Stats: 887690 lines in 180 files changed: 887689 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/shenandoah-jdk8u/pull/50.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah-jdk8u.git pull/50/head:pull/50

PR: https://git.openjdk.org/shenandoah-jdk8u/pull/50