RFR: 8319323: FFM: Harmonize the @throws tags in the javadocs

[Per Minborg]

This PR proposes to harmonize the @throws tags in the javadocs for the FFM API.

The @throws tags are using a bit different principles with respect to formatting and ending with a period or not.

Looking at some prominent Java classes like `List` and `Stream`, they:

1) Indent such that multi-line texts align with the beginning of the Exception type
2) Do not have a period after the text.

Some of the tags in the FFM classes already conform to these bullets. This PR proposes to make them all do.

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Commit messages:
 - FFM: Harmonize the @throws tags in the javadocs
 - Merge branch 'master' into javadoc-throws
 - Harmonize some of the javadoc throws

Changes: https://git.openjdk.org/jdk/pull/16478/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16478&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319323
  Stats: 455 lines in 10 files changed: 4 ins; 1 del; 450 mod
  Patch: https://git.openjdk.org/jdk/pull/16478.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16478/head:pull/16478

PR: https://git.openjdk.org/jdk/pull/16478