RFR: JDK-8321984: IGV: Upgrade to Netbeans Platform 20 [v3]

[Tobias Holenstein]

> Upgraded IGV and dependencies to the newest Netbeans Platform 20 which was released on December 2023.
> 
> Tested that IGV still behaves as expected after the upgrade.

Tobias Holenstein has updated the pull request incrementally with two additional commits since the last revision:

 - remove requirement for nashorn
 - make IGV build work with mainline JDK version

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17106/files
  - new: https://git.openjdk.org/jdk/pull/17106/files/b64adb13..f986934d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17106&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17106&range=01-02

  Stats: 146 lines in 2 files changed: 0 ins; 143 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/17106.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17106/head:pull/17106

PR: https://git.openjdk.org/jdk/pull/17106