RFR: 8187591: -Werror turns incubator module warning to an error

[Adam Sotona]

-Werror turns incubator module warning to an error
This patch disables incubating module warning at compile time when "preview" lint category is disabled.
It also adds a test, adjusts "preview" lint category description  and updates javac man pages.

Please review.

Thanks,
Adam

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Commit messages:
 - updated man page
 - added test
 - 8187591: -Werror turns incubator module warning to an error

Changes: https://git.openjdk.org/jdk/pull/16454/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16454&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8187591
  Stats: 26 lines in 5 files changed: 16 ins; 0 del; 10 mod
  Patch: https://git.openjdk.org/jdk/pull/16454.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16454/head:pull/16454

PR: https://git.openjdk.org/jdk/pull/16454