commands/resize: don't consider 1px resizes to be invalid

A "resize shrink width 1px" will cause grow_x to be 0 while grow_width is -1,
incorrectly rejecting the command even though the resize is not a noop.  Fix
this by checking width/height instead of x/y.

sway/commands/resize.c

@@ -224,7 +224,7 @@ static struct cmd_results *resize_adjust_floating(uint32_t axis,
 	} else if (axis == WLR_EDGE_LEFT) {
 		grow_x = -grow_width;
 	}
-	if (grow_x == 0 && grow_y == 0) {
+	if (grow_width == 0 && grow_height == 0) {
 		return cmd_results_new(CMD_INVALID, "Cannot resize any further");
 	}
 	con->x += grow_x;