RFR: 8207957: TableSkinUtils should not contain actual code implementation

[Hadzic Samir]

Allright, this is a fix for JDK-8207957

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Commits:
 - 969ebb51: Fixing TableColumnHeaderTest
 - 9d379619: Removing Tablecolumnbasehelper
 - 4fe020fc: Fix javadoc for TableColumnHeader
 - c422c80f: Minor modification and uni test added.
 - b2bdfb5b: Change resizeColumn to protected without static in order to be able to override
 - 3b9b7903: Second option for resizeColumnToFitContent in TableColumnHeader
 - d91c56e5: First attempt to extract resizeColumnToFitContent

Changes: https://git.openjdk.java.net/jfx/pull/6/files
 Webrev: https://webrevs.openjdk.java.net/jfx/6/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8207957
  Stats: 523 lines in 4 files changed: 330 ins; 187 del; 6 mod
  Patch: https://git.openjdk.java.net/jfx/pull/6.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/6/head:pull/6

PR: https://git.openjdk.java.net/jfx/pull/6