Provide sqlx magic

[nkitsaini]

The magic is just a thin wrapper over jupysql.
After this change %load_ext sqlx can be used to load sqlx magic and can be used as regular %sql magic.

  # Line usage
  %sqlx SELECT * FROM mytable
  result = %sqlx SELECT 1

  # Cell usage
  %%sqlx
  DELETE FROM mytable
  %%sqlx
  DROP TABLE mytable