Optionally handle user identifier as case-insensitive

[kdambekalns]

When using an identity provider that allows to log in with [email protected] as well as [email protected] this will create two distinct accounts in Neos. So when the user does this, confusion ensues, as the changes from yesterday are now seemingly gine (distinct workspaces for the user of the two accounts).

When coming from an LDAP background the expectation probably is for this to be case-insensitive:

Although most common Distinguished Name attributes are case-insensitive (CommonName, Organization, , OrganizationDomain) it would be possible to have a case-insensitive RDN component within the Distinguished Name which should be evaluated in a case-sensitive fashion according to the MatchingRule that applies ot the LDAPSyntaxes.

For Active Directory the recommended identifier (at least in a Windows context) is the UPN (user principal name). And that would be handled as case-insensitive, too. At least usually.

All that being said, the package should have a way to enable case-insensitive handling of user identifiers.