Add CSRF Support to the LDAP Guard

[ChadSikorra]

I should implement CSRF support in the Guard. To do this I will need to:

• Add csrf_parameter to the config, default to: _csrf_token
• Add csrf_token_generator to the config, default to: security.csrf.token_manager
• Add csrf_protection to the config, default to: false

Though this is different from how it's traditionally configured for a Symfony form (only have to specify the csrf_token_generator to enable it). I feel like enabling it via a bool true/false is a more explicit route to go.