Rewriting the scope_all benchmark in Sequel and Raw

@sem Just to make myself sure. Since this is graph with commit data, you want me to include here commits for sequel and pg. Therefore it would have 3 lines (AR, sequel, pg) and graph would look something like this:

Maybe better place to display results for older Rails releases would be here?
https://rubybench.org/rails/rails/releases?result_type=activerecord/postgres_scope_all