Add support for JDK23

[athre0z]

JDK23 is currently in release-candidate status and expected to reach GA on 17th Sep. Attempting to profile it currently results in the following error:

ERRO[1084] Failed to handle new anonymous mapping for PID 2338658: JVM symbol 'CompiledMethod.Sizeof' not found

[athre0z]

Probably related:

• openjdk/jdk@83eba86 merges CompiledMethod into nmethod
• openjdk/jdk@bdcc240 removes nmethod._dependencies_offset
• openjdk/jdk@b704e91241b0
  • CodeBlob::frame_comp changed int -> int16_t
  • Nmethod::_metadata_offset changed int -> uint16_t

[athre0z]

I didn't complete this before my last day at Elastic, but my patches for the progress so far live here: athre0z@e25c90d

It seemed to be generally working, though it still needs more testing and probably also some debugging. I had noticed a small percentage of unsymbolized frames.

[fabled]

Working on this now, wip tree at https://github.com/fabled/opentelemetry-ebpf-profiler/tree/tt-jdk23

I believe the metadata and immutable data fixup should resolve majority of issue. But will still follow up with further additional comments and documentation.