RFR: 8343296: IGV: Show pre/main/post at CountedLoopNodes

[Christian Hagedorn]

It's sometimes difficult to keep track of which counted loops are pre, main or post loops. This patch adds this property to `CountedLoops`, similarly to the other node info that we print, for example, like a method name for a `CallStaticJava`.

This is achieved by emitting a new property to `CountedLoopNodes` and then extending the node info filter in IGV. This will show the pre/main/post info like the other node info below the node name:

![image](https://github.com/user-attachments/assets/69abe3f4-3e97-4dfe-983a-0153057b1a8d)

Thanks to @robcasloz for helping me with the IGV filter changes!

Thanks,
Christian

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

Commit messages:
 - 8343296: IGV: Show pre/main/post at CountedLoopNodes

Changes: https://git.openjdk.org/jdk/pull/21788/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21788&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343296
  Stats: 30 lines in 4 files changed: 30 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/21788.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21788/head:pull/21788

PR: https://git.openjdk.org/jdk/pull/21788