RFR: 8345773: Class-File API debug printing capability [v3]

[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:

  improved javadoc

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/22634/files
  - new: https://git.openjdk.org/jdk/pull/22634/files/7c481059..6fdc3c43

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22634&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22634&range=01-02

  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 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