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

Even when the text begins with '='.

Change-Id: I6e0a995f3042240b9f78068b5d0b9b758eb253ed
(cherry picked from commit ca50752c34de4477c696471b707e1b8136e27661)
Reviewed-on: https://gerrit.libreoffice.org/8122
Tested-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Reviewed-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
(cherry picked from commit 563516fc10f1590a5987606de5444643b1b83747)
Reviewed-on: https://gerrit.libreoffice.org/8130
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>