Feature request description

https://github.com/sourcegraph/accounts/issues/579 would like to use GraphQL to gather user information for all users that have a specific feature flag set, this functionality will be useful for them to help keep up with user lists.

Is your feature request related to a problem? If so, please describe.

Currently, GraphQL doesn't have a constructible query to return users with feature flags set.

Describe alternatives you've considered.

Additional context

https://github.com/sourcegraph/accounts/issues/579 believe that getting user information such as username, email, display_name, created_at, updated_at, deleted_at from all the users that have a specific feature flag set would be advantageous information to monitor and maintain users.