[jfx20] RFR: 8290863: Update the documentation of Virtualized controls to include the best practice of not using Nodes directly in the item list [v5]

[Ajit Ghaisas]

> This PR adds a warning about inserting Nodes directly into the virtualized containers such as ListView, TreeView, TableView and TreeTableView. It also adds code snippets showing the recommended pattern of using a custom cell factory for each of the virtualized control.

Ajit Ghaisas has updated the pull request incrementally with one additional commit since the last revision:

  Review fixes

-------------

Changes:
  - all: https://git.openjdk.org/jfx/pull/995/files
  - new: https://git.openjdk.org/jfx/pull/995/files/7b441fbf..84423f5a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=995&range=04
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=995&range=03-04

  Stats: 24 lines in 5 files changed: 3 ins; 0 del; 21 mod
  Patch: https://git.openjdk.org/jfx/pull/995.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/995/head:pull/995

PR: https://git.openjdk.org/jfx/pull/995