Fix 2FA-based login for LDAP users
The OTP input form is shared by both LDAP and standard logins, but when
coming from an LDAP-based form, the form parameters aren't nested in a
Hash based on the resource_name value.
Now we check for a nested remember_me parameter and use that if it
exists, or fall back to the non-nested parameters if it doesn't.
Somewhat confusingly, the OTP input form does nest parameters under
the resource_name, regardless of what type of login we're coming from,
so that allows everything else to work as normal.