Verifies issue creation for a missing `Signature-Input` header.
Issue reported: {
    issue : {
        code : SRIMessageSignatureIssue
        details : {
            sriMessageSignatureIssueDetails : {
                error : MissingSignatureInputHeader
                integrityAssertions : [
                ]
                request : {
                    requestId : <string>
                    url : http://127.0.0.1:8000/inspector-protocol/resources/sri-message-signature-test.php?signature=signature%3D%3AgHim9e5Pk2H7c9BStOmxSmkyc8%2BioZgoxynu3d4INAT4dwfj5LhvaV9DFnEQ9p7C0hzW4o4Qpkm5aApd6WLLCw%3D%3D%3A
                }
                signatureBase :
            }
        }
    }
}