Move IsLittleEndianCached and IsEvalSupportedCached to src/shared/util.js

Rather than duplicating the lookup and caching in multiple files, it seems easier to simply move all of this functionality into `src/shared/util.js` instead.
This will also help avoid a bunch of ESLint errors once the `no-shadow` rule is eventually enabled.

src/core/function.js

@@ -17,19 +17,12 @@ import {
   FormatError,
   info,
   isBool,
-  isEvalSupported,
-  shadow,
+  IsEvalSupportedCached,
   unreachable,
 } from "../shared/util.js";
 import { isDict, isStream } from "./primitives.js";
 import { PostScriptLexer, PostScriptParser } from "./ps_parser.js";
 
-const IsEvalSupportedCached = {
-  get value() {
-    return shadow(this, "value", isEvalSupported());
-  },
-};
-
 class PDFFunctionFactory {
   constructor({ xref, isEvalSupported = true }) {
     this.xref = xref;