* [MISC] Validate all sections of ACLs on startup
This change ensure that all sections of the `access_control` key are validated on startup.
* Change error format to clearly identify values
* added support for listing multiple domains and multiple subjects
* updated documentation to show use of multiple domains and subjects
* updated config.template.yml to display multiple domains as a list
* updated config.template.yml to display multiple subjects as a list
* updated docs/configuration/access-control.md to display multiple domains as a list
* updated docs/configuration/access-control.md to display multiple subjects as a list
* removed redundant check that always returned true
* Commentary definition for `weak`