Changes proposed in this pull request:

This PR introduces a new rendering API for the showContextMenu and hideContextMenu options and deprecates the old API. The old API will be dropped in Blueprint 6.

Previously these functions would allow users to pass in an object with domRenderer and domUnmounter options which were implemented via ReactDOM.render and ReactDOM.unmountComponentAtNode respectively. This API does not work for React 18 which requires tracking a root node between the render and unmount stages. To allow for this, the new API instead allows passing a single render function which should return a function that unmounts the rendered node.

The default implementation still uses React 16 compatible defaults as before. In Blueprint 6 we will be making a few breaks here:

1. Remove the DOMMountOptions<T> type from the options prop of showContextMenu
2. Remove the options parameter of hideContextMenu
3. Change the default implementation of the render method to use React 18 compatible methods. It will look something like:

const defaultRenderer: ShowContextMenuDOMRenderer = (element, container) => {
    const root = ReactDOMClient.createRoot(container);
    root.render(element);
    return () => root.unmount();
}