fdo#72491: Always set input as text when that's requested.

Even when the text begins with '='.

(cherry picked from commit ca50752c34de4477c696471b707e1b8136e27661)

Conflicts:
	sc/source/core/data/column3.cxx

Change-Id: I6e0a995f3042240b9f78068b5d0b9b758eb253ed
Reviewed-on: https://gerrit.libreoffice.org/8123
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>