[jdk18] RFR: 8278604 SwingSet2 table demo does not have accessible description set for images

[Artem Semenov]

SwingSet2 demo is often used to check accessibility for different Swing components and has some shortcomings. The major one is that images within the table demo do not have accessible description set which makes accessibility perform differently on different platforms when navigating the table with screen narrator enabled.

This is the next step after the solution [JDK-8277497](https://bugs.openjdk.java.net/browse/JDK-8277497), in which we forwarded the description from the icon into the label description so that this fix was possible.

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Commit messages:
 - 8278604 SwingSet2 table demo does not have accessible description set for images

Changes: https://git.openjdk.java.net/jdk18/pull/31/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk18&pr=31&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8278604
  Stats: 9 lines in 1 file changed: 9 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk18/pull/31.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk18 pull/31/head:pull/31

PR: https://git.openjdk.java.net/jdk18/pull/31