[jdk21u-dev] RFR: 8335619: Add an @apiNote to j.l.i.ClassFileTransformer to warn about recursive class loading and ClassCircularityErrors

[Francesco Andreuzzi]

Almost clean backport of JDK-8335619, except for a conflict in the copyright header (year). Adds useful information for users of `java.lang.instrument`.

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Commit messages:
 - Backport eec0e155f303ff4bbdab172765ca7c92c2b94cbd

Changes: https://git.openjdk.org/jdk21u-dev/pull/2012/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2012&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8335619
  Stats: 21 lines in 1 file changed: 17 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2012.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2012/head:pull/2012

PR: https://git.openjdk.org/jdk21u-dev/pull/2012