Support `highContrast` attribute on `DecorationRenderOptions`

<!-- ⚠️⚠️ Do Not Delete This! feature_request_template ⚠️⚠️ --> <!-- Please read our Rules of Conduct: https://opensource.microsoft.com/codeofconduct/ --> <!-- Please search existing issues to avoid creating duplicates. --> <!-- Describe the feature you'd like. --> The `DecorationRenderOptions` object has `dark` and `light` attributes to allow overriding options for dark and light themes, respectively. However, it does not have a `highContrast` attribute for overriding options for high contrast themes. It would be nice to have such an attribute to enable such customization