Fix history steps not being given to Line tool endpoint movements (#3739)

start transaction when dragging line endpoints to enable abort

Author: Ayush2k02

editor/src/messages/tool/tool_messages/shape_tool.rs

@@ -789,6 +789,7 @@ impl Fsm for ShapeToolFsmState {
 				) && clicked_on_line_endpoints(layer, document, input, tool_data)
 					&& !input.keyboard.key(Key::Control)
 				{
+					responses.add(DocumentMessage::StartTransaction);
 					return ShapeToolFsmState::DraggingLineEndpoints;
 				}