RFR: 8367689: Revert removal of several compilation-related vmStructs fields

[Francesco Andreuzzi]

#23782 ([JDK-8315488](https://bugs.openjdk.org/browse/JDK-8315488)) removed several vmStructs fields. A small subset was used in Async-Profiler:

CiEnv* _env
CompileTask* _task
ciMethod* _method


I propose a small patch to bring them back. It helps third-party tools in building useful features on the JDK. For example, Async-Profiler uses these fields to display the current method being compiled in a compiler thread.

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Commit messages:
 - ops
 - remove indent
 - bring back fields

Changes: https://git.openjdk.org/jdk/pull/27318/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27318&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8367689
  Stats: 108 lines in 15 files changed: 68 ins; 0 del; 40 mod
  Patch: https://git.openjdk.org/jdk/pull/27318.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27318/head:pull/27318

PR: https://git.openjdk.org/jdk/pull/27318