RFR: 8313651: Add 'final' keyword to public property methods in controls

[Andy Goryachev]

In the Control hierarchy, all property accessor methods must be declared `final`.

Added a test to check for missing `final` keyword and added the said keyword where required.

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Commit messages:
 - whitespace
 - added final keyword
 - test

Changes: https://git.openjdk.org/jfx/pull/1213/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1213&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8313651
  Stats: 283 lines in 8 files changed: 239 ins; 0 del; 44 mod
  Patch: https://git.openjdk.org/jfx/pull/1213.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1213/head:pull/1213

PR: https://git.openjdk.org/jfx/pull/1213