RFR: 8258663: Fixed size TableCells are not removed from sene graph when column is removed

[Marius Hanl]

This PR fixes an issue, where table cells are not removed from the table row when the corresponding table column got removed. This will lead to empty "ghost" cells laying around in the table.
This bug only occurs, when a fixed cell size is set to the table.

I also added 3 more tests beside the mandatory test, which tests my fix.
1 alternative test, which tests the same with no fixed cell size set.
The other 2 tests are testing the same, but the table columns are set invisible instead.

-> Either the removal or setVisible(false) of a column should both do the same: Remove the corresponding cells, so that there are no empty cells.
Therefore, the additional tests make sure, that the other use cases (still) works and won't break in future (at least, without red tests ;)).
See also: TableRowSkinBase#updateCells(boolean)

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Commit messages:
 - 8258663: Fixed issue, where TableRows with fixedCellSize set do not remove cells when the corresponding column is removed

Changes: https://git.openjdk.java.net/jfx/pull/444/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=444&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8258663
  Stats: 166 lines in 2 files changed: 159 ins; 1 del; 6 mod
  Patch: https://git.openjdk.java.net/jfx/pull/444.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/444/head:pull/444

PR: https://git.openjdk.java.net/jfx/pull/444