Regression introduced in 69d6222481.
In that commit the `Depth` option of the placement started to override
the snap toggle. So only the `Suface` value had snap.
This commit also changes the behavior when triggering Placement.
Previously, snapping was forcefully enabled (in the case of `Surface`)
and snapping elements other than Face were used.
Now snap is only enabled if toggle is enabled.
c02f2f4947