owncloud/core

Security: Add new system config to enforce strict login check with user backend

Adds new system config to enforce strict login check for password
in user backend, meaning only login name typed by user would be validated.
With this configuration enabled, e.g. additional check for email will
not be performed.

https://github.com/owncloud/core/pull/37569
https://github.com/owncloud/user_ldap/pull/581