Implement selectedOptions for select[multiple]

[jakeboone02]

Is your feature request related to a problem? Please describe.

I'm converting tests from Jest to Bun and using happy-dom as recommended by the Bun docs. To test some of the React components, I access the selectedOptions property of the rendered <select multiple> element. This property is always undefined in happy-dom. No code, issues, PRs, etc. in this repo mention the property.

Describe the solution you'd like

Implement HTMLSelectElement#selectedOptions.

Describe alternatives you've considered

Sticking with jsdom for now.

Additional context

N/A