When pasting in place over a layer group or a content-locked item,
change the paste type to NEW_LAYER_IN_PLACE, rather than NEW_LAYER,
so that the new layer is still pasted in the right location.

Additionally, avoid showing the "Pasted as new layer because ..."
message when pasting over a layer group or a content-locked item,
when the paste type is NEW_LAYER[_IN_PLACE] to begin with.