fdo#82151 when constructing column object, replace m_aCurrentRow by a function

The passed m_aCurrentRow becomes out-of-date as soon as the current row changes.
This also hides an implementation detail of ORowSet to ORowSet(Data)Column.

Functional squelch of the following master commits:
  Change-Id: Ib9188743e5dd6dec240e9f5fd3fd9655c6761abc
  commit id: 03a2b4a80c5854bcb8520f2a43e485b98e3eba8f

  Change-Id: I527cc35ae120cf083f7c69a9a23526839a2bbddb
  commit id: 90b09303ef4f9163428107be7b8db23022ce10b7

  Change-Id: If813a1544ec9a5dac6f87197982d10576c91cd8c
  commit id: 5be4407d0716f78acdcdf24de135af91f17e51be

+ keep older behaviour of confusing no value and null value.

Change-Id: Ib9188743e5dd6dec240e9f5fd3fd9655c6761abc
Reviewed-on: https://gerrit.libreoffice.org/10796
Reviewed-by: David Tardon <dtardon@redhat.com>
Tested-by: David Tardon <dtardon@redhat.com>