fdo#84295 change context menu 'Style' entry to 'Format'

Change-Id: I177573294643bf9410bb42a3708b719250ff4a0c
Reviewed-on: https://gerrit.libreoffice.org/13329
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>