fix(axe.d.ts): add typings for preload options object

[blutorange]

Adds the TypeScript typings for passing an object to the preload setting for axe.run, as documented here: https://www.deque.com/axe/core-documentation/api-documentation/#preload-configuration-details

Specifying an object

axe.run(
  {
    preload: { assets: ['cssom'], timeout: 50000 }
  },
  (err, results) => {
    // ...
  }
);

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[straker]

Thanks for the update.

Reviewed for security.

[straker]

@blutorange You'll need to sign the CLA before we can get this merged.

[blutorange]

@straker I already did that when I created the commit, but it somehow does not seem to recognize it... strange

[straker]

Looks like the CLA github action isn't working at the moment? I looked at the CLA dashboard on our end and you have indeed signed it, so I'll go ahead and merge this.