Allow configuring CORS asynchronously for express

[michieldewilde]

Packages used:

• apollo-server (2.9.13)
• apollo-server-express (2.9.13)

Expected

By using the applyMiddleware function to connect apollo-server to express you can pass on cors option.
This cors option can be a Boolean or a CorsOptions object.
The apollo-server-express uses the cors package.
This package allows a third option to be passed: CorsOptionsDelegate.
This option allows CORS to be configured asynchronously.
Type definition: https://github.com/DefinitelyTyped/DefinitelyTyped/blob/31483b781ac30f98bdf4d40a517e921f2fc2ce37/types/cors/index.d.ts#L25

For the sake of completion this option should be available.

export interface GetMiddlewareOptions {
    cors?: corsMiddleware.CorsOptions | corsMiddleware.CorsOptionsDelegate | boolean;
}

[tslater]

Is this merged? Shouldn't this be closed?