RFR: 4265389: JSplitPane does not support ComponentOrientation

[Prasanta Sadhukhan]

JSplitPane's support of CompoentOrientation is not present so if orientation is RTL, it still renders left component on left and right component on left instead of other way around..
Fix to make it support RTL orientation

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Commit messages:
 - 4265389: JSplitPane does not support ComponentOrientation

Changes: https://git.openjdk.org/jdk/pull/20214/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20214&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-4265389
  Stats: 84 lines in 2 files changed: 80 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/20214.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20214/head:pull/20214

PR: https://git.openjdk.org/jdk/pull/20214