Add detection for (non-conforming) required authentication on ServiceRoot

[jautor]

Ran into a case where an implementation was wrongly requiring authentication on all resources, including the ServiceRoot (/redfish/v1) resource. While this is probably best classified as a protocol violation, it does halt the validation. If the user is made aware of this, they can work around it by using a local cached copy of /redfish/v1 with CacheMode of "Prefer". But as the tool only returns this as a connection error, it's not clear that this is the issue.

Tool should at least detect auth faults here and report them specifically for this case. Even better would be to add a fallback for this case - as in, if request returns auth error, attempt with provided credentials to see if that works - and flag this as an error in the report.

[mraineri]

Given the change in the tool to use the Python library, it should be performing authentication automatically on all resources (including ServiceRoot).