[jdk18] RFR: 8280592: Small javadoc tweaks to foreign API

[Maurizio Cimadamore]

This patch fixes some inconsistencies in the foreign API javadoc. The main fix is to make javadoc of all predicate methods consistent, and to use the `@return` tag where appropriate, as to avoid duplication.

There were also minor fixes in the package-level javadoc (one typo) and in `ValueLayout` (where hyphenation in *bit-alignment* has been dropped).

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Commit messages:
 - Initial push

Changes: https://git.openjdk.java.net/jdk18/pull/113/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk18&pr=113&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8280592
  Stats: 91 lines in 12 files changed: 0 ins; 42 del; 49 mod
  Patch: https://git.openjdk.java.net/jdk18/pull/113.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk18 pull/113/head:pull/113

PR: https://git.openjdk.java.net/jdk18/pull/113