Feat: Improve pagination info

[frankdugan3]

Is your feature request related to a problem? Please describe.

Relay support #25 will add page_info to the relay version of the GraphQL schema. It would be ideal to have similar page info added to the non-relay pagination schemas.

Describe the solution you'd like

Basically, it would be nice to have all the pagination conveniences that AshPhoenix gives, such as next_page?, page_number, last_page, etc.

For example

{
  posts(limit: 10, offset: 2) {
    count
    has_next_page
    has_previous_page
    page_number
    last_page
    results {
      title
      body
    }
  }
}

[xantrac]

#320