Simplify the getUuid helper function

We can remove most feature testing from this helper function, with the exception of `randomUUID` since that's only available in "secure contexts", and also remove the fallback code-path.
Note that this code was only added for Node.js compatibility, and it's no longer necessary now that the minimum support version is `20`; see also https://developer.mozilla.org/en-US/docs/Web/API/Crypto#browser_compatibility

Finally, this patch also adds a basic unit-test for the helper function.

src/shared/util.js

@@ -1075,21 +1075,12 @@ function normalizeUnicode(str) {
 function getUuid() {
   if (
     (typeof PDFJSDev !== "undefined" && PDFJSDev.test("MOZCENTRAL")) ||
-    (typeof crypto !== "undefined" && typeof crypto?.randomUUID === "function")
+    typeof crypto.randomUUID === "function"
   ) {
     return crypto.randomUUID();
   }
   const buf = new Uint8Array(32);
-  if (
-    typeof crypto !== "undefined" &&
-    typeof crypto?.getRandomValues === "function"
-  ) {
-    crypto.getRandomValues(buf);
-  } else {
-    for (let i = 0; i < 32; i++) {
-      buf[i] = Math.floor(Math.random() * 255);
-    }
-  }
+  crypto.getRandomValues(buf);
   return bytesToString(buf);
 }
 

test/unit/util_spec.js

@@ -18,6 +18,7 @@ import {
   bytesToString,
   createValidAbsoluteUrl,
   getModificationDate,
+  getUuid,
   string32,
   stringToBytes,
   stringToPDFString,
@@ -248,4 +249,12 @@ describe("util", function () {
       expect(getModificationDate(date)).toEqual("31410609020653");
     });
   });
+
+  describe("getUuid", function () {
+    it("should get uuid string", function () {
+      const uuid = getUuid();
+      expect(typeof uuid).toEqual("string");
+      expect(uuid.length).toBeGreaterThanOrEqual(32);
+    });
+  });
 });