var-naming[no-role-prefix] rule should accept collection roles vendor prefix

[nervo]

Let's say i'm working in a "foo" company, where we have decided to write our own collections. Our collections would be named foo.system or - for instance - foo.nginx for more specifics and nginx related roles.
What if we want to mix our collections with some ones found on ansible-galaxy ?

Prefixing role's variables with only role name (nginx_ in this situation) like it's checked by https://ansible.readthedocs.io/projects/lint/rules/var-naming/ will certainly going to collide between collections.

I think it should be allowed (and a good practice too) to prefix roles variables names with collection vendor names, such as foo_nginx_

I know there is a var_naming_pattern option that we can use, but it will break all the substance of the check, which is to verify var naming role by role.