RFR: 8251480: TableColumnHeader: calc of cell width must respect row styling [v3]

[Robert Lichtenberger]

> This fix respects a row factory, if present.
> It will put the cell that is used to measure the column width as child below the row.
> In that way the row's style will be used.

Robert Lichtenberger has updated the pull request incrementally with one additional commit since the last revision:

  8251480: TableColumnHeader: calc of cell width must respect row styling
  
  Test readability improved.

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Changes:
  - all: https://git.openjdk.java.net/jfx/pull/757/files
  - new: https://git.openjdk.java.net/jfx/pull/757/files/af582570..960e5012

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=757&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=757&range=01-02

  Stats: 13 lines in 1 file changed: 6 ins; 6 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/757.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/757/head:pull/757

PR: https://git.openjdk.java.net/jfx/pull/757