Resolves: tdf#145722 don't propose MOVE from AcceptDrop if not asked for MOVE
announce to dnd that tree supports COPY and MOVE, but on accepting a drop
return MOVE only if that's something the AcceptDrop has set as desirable.
a) makes ctrl+dnd to select 'copy' work for gtk, including gtk on wayland
b) makes gen correctly draw its copy dnd icon.
git show -w
Change-Id: Ie985f8c9201634afc5ae717fd2aef0dbc18a39e4
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/134440
Tested-by: Jenkins
Reviewed-by: Adolfo Jayme Barrientos <fitojb@ubuntu.com>