fix: move utility types out of .d.ts file to fix exported declaration files (#6315)

src/element/bounds.ts

@@ -23,6 +23,7 @@ import {
 import { rescalePoints } from "../points";
 import { getBoundTextElement, getContainerElement } from "./textElement";
 import { LinearElementEditor } from "./linearElementEditor";
+import { Mutable } from "../utility-types";
 
 // x and y position of top left corner, x and y position of bottom right corner
 export type Bounds = readonly [number, number, number, number];