RFR: 8309602: update JVMTI history table for jdk 21

[Serguei Spitsyn]

This is a minor update of the `jvmti.xml` file.
The JVM TI history table needs to be updated to list new capability, functions and events added to support virtual threads as a permanent feature in JDK 21. Also, it should list a minor update with the `Implementation Note` that dynamic loading of agents into a running VM is now specified to print a warning (JEP 451).
The JVM TI history table is maintained for convenience only and does not require a CSR.

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

Commit messages:
 - 8309602: update JVMTI history table for jdk 21

Changes: https://git.openjdk.org/jdk/pull/14352/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14352&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8309602
  Stats: 18 lines in 1 file changed: 17 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/14352.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14352/head:pull/14352

PR: https://git.openjdk.org/jdk/pull/14352