Kernel: Fixed column number issue in DynamicTreeTableUIProviderBase

DynamicTreeTableUIProviderBase did not take into account hidden
(invisible) columns for numbering. With this, column numbers changed,
whenever a column became invisible.

Now the column number is correct - also invisible columns are counted.

Issue-Ref: 4014
Issue-Url: https://af3-developer.fortiss.org/issues/4014


Signed-off-by: Andreas Bayha <bayha@fortiss.org>