Fix DomException when simplifying nested elements caused by invalid attribute names

[dbowring]

Copies the same fix for copying invalid property names (such as ") used in _setNodeTag to _simplifyNestedElements.

You can reproduce this error running the following code in node (with jsdom installed):

const { JSDOM } = require("jsdom");
const Readability = require("./Readability.js");

const sampleHTML = '<div "=""><div><div>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</div></div></div>';
const dom = new JSDOM(sampleHTML, { contentType: "text/html" });
const readability = new Readability(dom.window.document);
const parsed = readability.parse();
console.log(parsed.textContent);

Without the fix:

$ node demo.js  

./readability/node_modules/jsdom/lib/jsdom/living/helpers/validate-names.js:10
    throw DOMException.create(globalObject, [`"${name}" did not match the Name production`, "InvalidCharacterError"]);
    ^
[DOMException [InvalidCharacterError]: """ did not match the Name production]

Node.js v20.18.0

With the fix:

$ node demo.js
Lorem ipsum dolor sit amet, consectetur adipiscing elit.

[dbowring]

Added the demo from the original comment as a test (70cedd6), but it also requires changes the way attributes are compared for the tests (to ignore invalid attributes, if they are there they are fine, but if we need to remove them that should also be fine), so you may wish to drop that commit if the test changes are not acceptable.