Using ecto_type with from_schema causes compile dependency

[woylie]

Using the :from_schema tuple in the ecto_type option causes a compile dependency to the referenced Ecto schema module.

@derive {
  Flop.Schema,
  filterable: [],
  sortable: [],
  join_fields: [
    some_field: [
      binding: :some_binding,
      field: :some_field,
      ecto_type: {:from_schema, SomeSchema, :some_field}
    ]
  ]
}