RFR: 8374347: StyleAttributeMap.Builder.setParagraphDirection()

[Andy Goryachev]

Renaming `setRTL(ParagraphDirection)` ->  `setParagraphDirection(ParagraphDirection)` in the `StyleAttributeMap.Builder` class.

This is a breaking change with low impact, ok since the feature is still incubating.

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Commit messages:
 - set paragraph direction

Changes: https://git.openjdk.org/jfx/pull/2021/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=2021&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8374347
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jfx/pull/2021.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/2021/head:pull/2021

PR: https://git.openjdk.org/jfx/pull/2021