Improve the provider selection. #9
Description
The problem
Currently we implement provider selection through the URL only. However this has the downside that for some providers that restrict some endpoints (like SNCF), we can't stop a request before executing it.
The solution
One way we could do this is move the providers info from URLs to a proper Struct, with information about which endpoints are allowed/disallowed, which will be integrated in Session via a map[string]bool (has O(1) complexity) allowing us not to waste bandwidth.
This may also allow us to have the SSL fingerprints public in those structs, though that's a question for another issue.
As always, I'm open to suggestions.