RFR: JDK-8304542: Convert use of internal VM::classFileVersion to ClassFileFormatVersion [v2]

[Mandy Chung]

> Replace calls to `jdk.internal.vm.VM::classFileVersion` with `java.lang.reflect.ClassFileFormatVersion.latest().major()`.   This also fixes jlink SystemModulesPlugin plugin to use CFFV API instead of hardcoding the class file version.

Mandy Chung has updated the pull request incrementally with one additional commit since the last revision:

  update copyright header

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13106/files
  - new: https://git.openjdk.org/jdk/pull/13106/files/4a6de284..027a82f8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13106&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13106&range=00-01

  Stats: 4 lines in 4 files changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/13106.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13106/head:pull/13106

PR: https://git.openjdk.org/jdk/pull/13106