RFR: JDK-8298200 Clean up raw type warnings in javafx.beans.property.* and com.sun.javafx.property.*

[John Hendrikx]

- Added generics (to package private or internal classes only)
- Minor clean-ups of code I touched (naming)
- Fixed incorrect use of generics
- Fixed raw type warnings

Note: some raw types have leaked into public API.  These could be fixed without incompatibilities.  For specifics see `JavaBeanObjectPropertyBuilder`.  The javadoc would have the method signatures change (`<T>` would be appended to the affected methods).  For now I've added a TODO there.

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Commit messages:
 - Generics clean up javafx.beans.property.* and com.sun.javafx.property.*

Changes: https://git.openjdk.org/jfx/pull/969/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=969&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8298200
  Stats: 139 lines in 38 files changed: 9 ins; 0 del; 130 mod
  Patch: https://git.openjdk.org/jfx/pull/969.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/969/head:pull/969

PR: https://git.openjdk.org/jfx/pull/969