RFR: 8359599: Calling refresh() for all virtualized controls recreates all cells instead of refreshing the cells

[Marius Hanl]

When calling `refresh()` on virtualized Controls (`ListView`, `TreeView`, `TableView`, `TreeTableView`), all cells will be recreated completely, instead of just refreshing them.

This is because `recreateCells()` of the `VirtualFlow` is called when `refresh()` was called. This is not needed, since refreshing the cells can be done much cheaper with `rebuildCells()`.

This will reset all cells (`index = -1`), add them to the pile and fill them back in the viewport with an index again. This ensures `updateItem()` is called.

The contract of `refresh()` is also a big vague, stating:

Calling {@code refresh()} forces the XXX control to recreate and repopulate the cells 
necessary to populate the visual bounds of the control.
In other words, this forces the XXX to update what it is showing to the user. 
This is useful in cases where the underlying data source has changed in a way that is not observed by the XXX itself.


As written above, recreating is not needed in order to fulfull the contract of updating what is shown to the user in case the underlying data source changed without JavaFX noticing (e.g. calling a normal Setter without any Property and therefore listener involved).

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Commit messages:
 - Calling refresh() for all virtualized controls recreates all cells instead of refreshing the cells

Changes: https://git.openjdk.org/jfx/pull/1830/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1830&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8359599
  Stats: 476 lines in 14 files changed: 316 ins; 109 del; 51 mod
  Patch: https://git.openjdk.org/jfx/pull/1830.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1830/head:pull/1830

PR: https://git.openjdk.org/jfx/pull/1830