Improve error messages for end users in AzureMFA gssp

[phavekes]

This issue is imported from pivotal - Originaly created at May 7, 2020 by Peter Havekes

All errors are shown as "Something went wrong, please try again". The logs show useful messages at the same moment. These error-messages can help users, of help our support-users to provide the right solution.

These error messages show up in the logs, and should also be shown on the user-facing error pages:

• The NameId from the Azure MFA assertion did not match the NameId provided during registration
• ADFS AuthnRequest requests ACS location but it is not configured in the list of allowed ACS locations
• Unable to validate Signature

EST. 4h

[phavekes]

(Peter Havekes - May 7, 2020)

[phavekes]

Possibly related: If an exception is trown during registration, the user is redirected to the /registration/ page, without any information. eg MailAttributeMismatchException

https://github.com/OpenConext/Stepup-Azure-MFA/blob/3866bfee49423079300531e89eb69709d25be792/src/Surfnet/AzureMfa/Application/Service/AzureMfaService.php#L225 (Peter Havekes - Dec 2, 2020)