Bug with custom role permissions validation

There are several issues related to the validation the occurs when creating custom roles

1. false values can be stored in the database. This adds unneeded overhead since we are only concerned with enabled permissions. All other permissions are assumed to be disabled by default.
2. Roles with permissions that are disabled via feature flag are able to stored. There should be a validation error when attempting to create a role with disabled permissions.
3. When unknown permissions are passed we get a generic JSON schema validation error (must be a valid json schema). We should return a more helpful error response.