RFR: 8343037: Missing @since tag on JColorChooser.showDialog overload

[Prasanta Sadhukhan]

[JDK-8051548](https://bugs.openjdk.org/browse/JDK-8051548) in Java 9 added a new overload of `JColorChooser.showDialog` but `@since` tag is missing..The fix also added couple of new methods to AbstractColorChooserPanel.java where also `@since` tag is added

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Commit messages:
 - 8343037: Missing @since tag on JColorChooser.showDialog overload
 - 8343037: Missing @since tag on JColorChooser.showDialog overload

Changes: https://git.openjdk.org/jdk/pull/21754/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21754&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343037
  Stats: 4 lines in 2 files changed: 4 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/21754.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21754/head:pull/21754

PR: https://git.openjdk.org/jdk/pull/21754