Add an example that re-uses a client #229
Description
I'm trying to re-use a client to implement an OIDC Auth Server with Axum, and I ran into the same issue as #193. It's really not clear as a casual user of this crate what the type of my client should be. I was trying to follow the examples - which are very easy to read, thank you! - but my first attempt at writing my own code gave me a mismatched type error that wraps to multiple lines on my terminal, which was very much not easy to read or make sense of.
It would be really helpful to have an example that demonstrates saving and re-using a client. Even better, it would be great to have some type aliases that cover common use-cases. As a user of this crate, I don't really care that something type-state-y is going on, so this feels like a chore to have to figure out on my own.