RFR: 8339972: Make a few fields in SortingFocusTraversalPolicy static

[Andrey Turbanov]

2 fields in javax.swing.SortingFocusTraversalPolicy could be made 'static':
1. FORWARD_TRAVERSAL = 0
2. BACKWARD_TRAVERSAL = 1

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Commit messages:
 - [PATCH] Make a few fields in SortingFocusTraversalPolicy static

Changes: https://git.openjdk.org/jdk/pull/20327/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20327&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339972
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/20327.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20327/head:pull/20327

PR: https://git.openjdk.org/jdk/pull/20327