Make the Pen tool only append new paths when Shift is held (#2102)

* Append to a path with shift

* Fixup transforms

* Revert unnecessary transform change

* Fix delete node button transaction

* Prevent artboard from being selected after making a new document

---------

Co-authored-by: Keavon Chambers <keavon@keavon.com>

editor/src/messages/dialog/new_document_dialog/new_document_dialog_message_handler.rs

@@ -25,18 +25,18 @@ impl MessageHandler<NewDocumentDialogMessage, ()> for NewDocumentDialogMessageHa
 
 				let create_artboard = !self.infinite && self.dimensions.x > 0 && self.dimensions.y > 0;
 				if create_artboard {
+					responses.add(Message::StartBuffer);
 					responses.add(GraphOperationMessage::NewArtboard {
 						id: NodeId::new(),
 						artboard: graphene_core::Artboard::new(IVec2::ZERO, self.dimensions.as_ivec2()),
 					});
 				}
 
-				responses.add(NodeGraphMessage::RunDocumentGraph);
-				responses.add(NodeGraphMessage::UpdateNewNodeGraph);
-
 				// TODO: Figure out how to get StartBuffer to work here so we can delete this and use `DocumentMessage::ZoomCanvasToFitAll` instead
+				// Currently, it is necessary to use `FrontendMessage::TriggerDelayedZoomCanvasToFitAll` rather than `DocumentMessage::ZoomCanvasToFitAll` because the size of the viewport is not yet populated
 				responses.add(Message::StartBuffer);
 				responses.add(FrontendMessage::TriggerDelayedZoomCanvasToFitAll);
+				responses.add(DocumentMessage::DeselectAllLayers);
 			}
 		}