tdf#112641 sc: always allow freezing at cell A1

tdf#112641 sc: always allow freezing at cell A1

For some good reasons, freezing rows and columns
doesn't work unless that cell is currently visible,
and that is almost guaranteed anyway since the
hisorical way of doing it was at the cursor.

However, since LO 5.2 there are menu and UNO commands
to freeze the first row and the first column.
It would be nice if these would work regardless
of where you are in the spreadsheet
(and keep you at that position too).

[If there is already a SPLIT (not freeze),
 then the bottom right quadrant is still
 the "position" that is maintained.]

[This "works" if the first row/column is hidden.
 When unhidden, the freeze will be in effect.
 I assume that is reasonable and doesn't need
 to be avoided for any reason.]

Change-Id: Iddc5d63adaad7ecfe6b5fb9b60ff3ec6274b0756
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/142128
Tested-by: Jenkins
Reviewed-by: Justin Luth <jluth@mail.com>
Reviewed-by: Eike Rathke <erack@redhat.com>