RFR: 8252387: Deprecate for removal css Selector and ShapeConverter constructors

[Bhawesh Choudhary]

Deprecate the public constructor of javafx.css.Selector and javafx.css.converter.ShapeConverter

 Constrcutor for class javafx.css.Selector should not be public as it is only extended by classes in same package. it
 should be changed to package-private Constrcutor for class javafx.css.converter.ShapeConverter should be private rather
 than public as its a singleton class.

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Commit messages:
 - 8252387: Deprecate for removal css Selector and ShapeConverter constructors

Changes: https://git.openjdk.java.net/jfx/pull/290/files
 Webrev: https://webrevs.openjdk.java.net/jfx/290/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8252387
  Stats: 14 lines in 2 files changed: 14 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/290.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/290/head:pull/290

PR: https://git.openjdk.java.net/jfx/pull/290