Fix Authorization header

[willoucom]

Fixes #89

Since getHeaderLine() can return a coma separated string, i add an explode and a foreach.

Updated tests to reflect the change

[omega3000]

I agree to this solution.
In my setup I provide a slim API for a frontend Vue application were I wanted to use basic auth to secure the API endpoint and a bearer token for user authentication. So my header looked like this:

Authorization: Basic <base64UserPasswd>, Bearer <jsonWebToken>

The approach from @willoucom made that work!

[tuupola]

AFAIK header which looks like below is invalid syntax.

Authorization: Basic <base64UserPasswd>, Bearer <jsonWebToken>

[nerdlibfront]

We occured the same issue in another scenario.
It seems that the combination of AWS ALB, EKS ingress, an apache pod and HTTP/2 leads to a duplication of the header somewhere down the road, resulting in a Header like:
Authorization: Basic foo,Basic foo

I agree that this is basically not the problem of the library, but it would add some resilience if the lib would just take the first header starting with "Basic".

[willoucom]

I agree with @tuupola , having 2 different authorization is invalid.
There are multiple discussions on the Internet about this header and it seems that nobody agrees on a solution.

However, I think the problem with some loadbalancers (e.g. amazon/scaleway/azure) duplicating the header can lead to a lot of problems for developers wanting to use this library (which I consider great).
To solve this problem, I can modify my patch to retrieve only the first element of the header and ignore the others, I think this will solve the problem caused by LBs and prevent misuse of the header (i.e. using multiple schemas in the same header).

What do you think about this alternative?