RFR: 8345773: Class-File API debug printing capability [v2]

[Adam Sotona]

> Class-File API lost debug printing capability with removal of the `j.l.classfile.components.ClassPrinter` in JDK-8345343.
> This PR adds `j.l.classfile.CompoundElement::toDebugString` method to restore the capability.
> 
> Please review.
> 
> Thank you,
> Adam

Adam Sotona has updated the pull request incrementally with one additional commit since the last revision:

  excluding impl fix from the PR

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/22634/files
  - new: https://git.openjdk.org/jdk/pull/22634/files/c10fb8ee..7c481059

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22634&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22634&range=00-01

  Stats: 39 lines in 1 file changed: 0 ins; 19 del; 20 mod
  Patch: https://git.openjdk.org/jdk/pull/22634.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22634/head:pull/22634

PR: https://git.openjdk.org/jdk/pull/22634