fdo#70998 change terms graphics/picture to image

not completely since changes in UI are not complete

Change-Id: I404af180fc4317204995217736f4e2bfd2cc7723
Reviewed-on: https://gerrit.libreoffice.org/9244
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>