RFR: 8343535: IGV: Colorize nodes on demand

[Tobias Holenstein]

<img width="292" alt="color" src="https://github.com/user-attachments/assets/ea050a39-5f1e-456b-adaa-2102d78b0f60">

<img width="697" alt="pick" src="https://github.com/user-attachments/assets/67569b5d-1d74-4a93-8a97-bb37c5bc9f93">

<img width="428" alt="nodes" src="https://github.com/user-attachments/assets/c8a994e3-9946-42ae-8701-34223a000a0c">

Adds new option to IGV to color selected nodes:
1) select some nodes
2) `Ctrl + C` or `View` -> `Color action`
3) pick a color and apply

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Commit messages:
 - Update ColorAction.java
 - JDK-8343535: IGV: Colorize nodes on demand

Changes: https://git.openjdk.org/jdk/pull/21925/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21925&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343535
  Stats: 109 lines in 6 files changed: 105 ins; 3 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/21925.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21925/head:pull/21925

PR: https://git.openjdk.org/jdk/pull/21925