RFR: 4265389: JSplitPane does not support ComponentOrientation [v4]

[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 right instead of other way around..
> Fix to make it support RTL orientation

Prasanta Sadhukhan has updated the pull request incrementally with one additional commit since the last revision:

  Prevent ComponentOrientation.UNKNOWN to be treated as RTL in previous fix

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Changes:
  - all: https://git.openjdk.org/jdk/pull/20214/files
  - new: https://git.openjdk.org/jdk/pull/20214/files/6017c687..b0ef1dbd

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20214&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20214&range=02-03

  Stats: 28 lines in 2 files changed: 13 ins; 11 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