Client applications should be able to use non-bearer authorization

[sentient-glare]

Currently it seems that client applications are forced to have their tokens interpreted as a Bearer token. This causes problems where other authentication schemes are required.

https://github.com/pyroscope-io/pyroscope-rs/blob/23fb2fdc3a7a7f7196f2a7811b90ea1360f4ce7f/src/session.rs#L230
https://docs.rs/reqwest/latest/src/reqwest/async_impl/request.rs.html#261

An option that allows the client to set the entire value of the Authorization header would be the fix for my use case.