Elytron - inconsistency between DMR and XSD representation of ldap-realm

There are inconsistencies between DMR and XSD representation of ldap-realm.

• According to XSD [1] from attribute from user-password-mapper is required in ldap-realm. According to DMR from attribute is "nillable" => true.
• According to XSD [2] every attribute (algorithm-from, hash-from, seed-from, sequence-from) from otp-credential-mapper is required in ldap-realm. According to DMR all these attributes are "nillable" => true.
• According to XSD [3] name of attribute from new-identity-attributes is required in ldap-realm. According to DMR name of attribute is "nillable" => true.

These inconsistencies should be unified.

[1] https://github.com/wildfly-security/elytron-subsystem/blob/82a3cfb2c1c7c87db71d84b79475ddab5193f904/src/main/resources/schema/wildfly-elytron_1_0.xsd#L1008
[2] https://github.com/wildfly-security/elytron-subsystem/blob/82a3cfb2c1c7c87db71d84b79475ddab5193f904/src/main/resources/schema/wildfly-elytron_1_0.xsd#L1031
[3] https://github.com/wildfly-security/elytron-subsystem/blob/82a3cfb2c1c7c87db71d84b79475ddab5193f904/src/main/resources/schema/wildfly-elytron_1_0.xsd#L1079