Abstract away or eliminate most of the mutation of the Elements array (#955)

src/element/textElement.ts

@@ -1,10 +1,10 @@
 import { measureText } from "../utils";
 import { ExcalidrawTextElement } from "./types";
-import { mutateTextElement } from "./mutateElement";
+import { mutateElement } from "./mutateElement";
 
 export const redrawTextBoundingBox = (element: ExcalidrawTextElement) => {
   const metrics = measureText(element.text, element.font);
-  mutateTextElement(element, {
+  mutateElement(element, {
     width: metrics.width,
     height: metrics.height,
     baseline: metrics.baseline,