Add Java 21

[Madjosz]

• Name: Java
• Version: 21 (LTS)
• Release Note/Changelog (since 17 LTS):
  • Simple Web Server
  • Pattern Matching for switch and records
  • Virtual Threads

  • Sequenced Collections

:+1: reaction might help to get this request prioritized.

[Feliks-WR]

PLEASE DO!