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

[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.

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Commit messages:
 - JDK-8304542: Convert use of internal VM::classFileVersion to ClassFileFormatVersion
 - Merge branch 'master' of https://github.com/openjdk/jdk into cff-version
 - Merge branch 'master' of https://github.com/openjdk/jdk into AddClassLoader_Proxy
 - Added JavaLangAccess::getLoaderNameID(ClassLoader loader)
 - Avoid long line of code
 - Add comments
 - Fix Indentation
 - Use classloaderName if not Null otherwise Objects.toIdentityString(ld)
 - Added specific ClassLoader object to Proxy IllegalArgumentException

Changes: https://git.openjdk.org/jdk/pull/13106/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13106&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8304542
  Stats: 22 lines in 5 files changed: 5 ins; 12 del; 5 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