Missing REST API users endpoint orderby parameters

[helgatheviking]

​Allowed orderby params in users endpoint

compared to

​Supported orderby params in `WP_Users_Query`

The rest endpoint is missing support for ordering by

• 'user_login' (or 'login')
• 'post_count'
• 'meta_value',
• 'meta_value_num'
• 'loginin'

I don't know how complex the meta would be, nor do I fully understand what login__in actually does, but for sure the endpoint is missing the ability to order by the user's login/username which can be different from the nicename.