RFR: 8306457: Classfile API components implementations should not be exposed

Wed Apr 19 17:07:57 UTC 2023

The jdk.internal.classfile.components package's interfaces have implementations in their nested classes, which are implicitly public and exported with the package. They are now moved to the impl package to avoid unwanted exposures. Fixed a few minor javadoc issues in the interfaces as well.

In conflict with #13021; one needs updating if the other is merged.

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Commit messages:
 - 8306457: Classfile API components implementations should not be exposed

Changes: https://git.openjdk.org/jdk/pull/13541/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13541&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306457
  Stats: 1770 lines in 8 files changed: 919 ins; 825 del; 26 mod
  Patch: https://git.openjdk.org/jdk/pull/13541.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13541/head:pull/13541

PR: https://git.openjdk.org/jdk/pull/13541