changed authinfo comparison from nil to empty struct

[lucamrgs]

The addAuthTo function in utils/http/http.go performs a check of httpOptions.Auth to be nil, as to check whether it was specified or not, for authentication information is an optional property.

But, an Authentication information should always be passed as property to the capability.Execute() function, hence it is always a struct: either completely empty, or not.

As a consequence, the check in utils/http/http.go addAuthTo is not correct, and the logic further checks for consistency in the field of an empty struct to add authInfo to the headers. This obviously fails, whereas instead it should not be checked, as no auth headers should be added if an empty authInfo struct is passed.

[lucamrgs]

So, many tests in unittest/utils/http/htpp_test.go leave the Auth information non specified, hence the check on empty struct alone will throw an error, because the supposed empty struct is in fact a nil.

In the overall SOARCA execution, it should never happen that authentication information is nil, but it should always be either a completely empty struct, or a non completely empty struct.

So at the moment, I just left both checks, but logically, there should never be a null authenticationInformation object passed to the http.Request util. What to do?