RFR: 8289357: (Tree)TableView is null in (Tree)TableRowSkin during autosize [v3]

[Marius Hanl]

> Initialize the `(Tree)TableView` when creating the measure row.
> This will guarantee, that we can access the `(Tree)TableView` in the `(Tree)TableRowSkin`, which is currently only null during the autosizing (It is always set otherwise).
> 
> With this change, a NPE is happening as the `(Tree)TableRow` currently assumes, that there must be a `VirtualFlow` somewhere in the scene (parent). I guard against this now.
> I remembered, that there is a ticket for the above behaviour here: https://bugs.openjdk.org/browse/JDK-8274065
> 
> Finally, the `(Tree)TableRow` must be removed after the autosizing and the index must be set to `-1` (as for the cell) so that e.g. `cancelEdit` is not triggered twice. Some tests catched that (see `test_rt_31015`).

Marius Hanl has updated the pull request incrementally with two additional commits since the last revision:

 - 8289357: Added test to verify, that no (Tree)TableRows remain after auto sizing
 - 8289357: Fix test which failed as the coutner increased by one due to the now correct row setup

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Changes:
  - all: https://git.openjdk.org/jfx/pull/805/files
  - new: https://git.openjdk.org/jfx/pull/805/files/e3a9545e..b6dcccdb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=805&range=02
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=805&range=01-02

  Stats: 27 lines in 3 files changed: 25 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jfx/pull/805.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/805/head:pull/805

PR: https://git.openjdk.org/jfx/pull/805