Harmonize TableWrapLayout2 and TableWrapData2 with Forms classes

Both the [TableWrapLayout2](https://github.com/eclipse-windowbuilder/windowbuilder/blob/master/org.eclipse.wb.rcp/src/org/eclipse/wb/internal/rcp/model/forms/layout/table/TableWrapLayout2.java) and [TableWrapData2](https://github.com/eclipse-windowbuilder/windowbuilder/blob/master/org.eclipse.wb.rcp/src/org/eclipse/wb/internal/rcp/model/forms/layout/table/TableWrapData2.java) are pretty old copies of the Forms classes which we have extended to store additional information during the layout.

We should separate the designer information from the layout algorithm to make sure that our implementation matches the actual implementation.

Start by comparing TableWrapLayout2.java and TableWrapData2.java with the corresponding Forms classes, then identify which information is used by the layout algorithm and which is designer-specific. Define the separation boundary before changing the implementation, and verify that layout behavior matches the actual Forms implementation while designer information remains available.

Written by the indexing model from the issue text.