RFR: 8311648: Refactor the Arena/Chunk/ChunkPool interface

[Johan Sjölen]

Hi,

This PR refactors the Arena code without introducing any changes in behavior. I believe that this leads to a much clearer API and that this will in turn simplify the maintenance of this code. `Chunk` is now much more "dumb", mainly acting as a way of interrogating the chunk of data that it is holding. The `ChunkPool` gains a more prominent role, being entirely responsible for the memory allocation strategy used. `Arena` is basically unchanged, as it orchestrates the usage of these two APIs. The `chop` and `next_chop` methods are re-defined to be static inside of `Chunk`, having an object `delete` itself  is very surprising, so I'm happy to get rid of that.

I hope that you agree with me on these changes!

Cheers,
Johan

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Commit messages:
 - One more comment
 - Remove comment sections
 - Missed two small issues
 - Move allocation responsibilities to ChunkPool
 - Remove operator new/delete
 - Make chop and next_chop static
 - Pointer style

Changes: https://git.openjdk.org/jdk/pull/14803/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14803&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311648
  Stats: 182 lines in 5 files changed: 63 ins; 67 del; 52 mod
  Patch: https://git.openjdk.org/jdk/pull/14803.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14803/head:pull/14803

PR: https://git.openjdk.org/jdk/pull/14803