Implement functionality that allows a User to Specify their own Auth Config

What

It would be flexible if the user could specify their own auth config. The user may want to perform browser whitelisting/blacklisting and other actions like providing custom scopes etc to be able to use refresh tokens.

Why

To allow a user to freely configure the extra functionality in AppAuth such as whitelisting or blacklisting browsers that a user can login through. It can also be used to allow connections to non-SSL endpoints on the OpenID Connect server, which is useful for running a local development cluster or in a test environment.

How

Allow a user to specify their own auth config which can be be consumed by AppAuth under the hood. This should have some defaults like the following code example if no options are specified.