Per [this discussion][arel-discussion] on the discourse forum, this is
an addition to Arel for supporting `@>` (contains) and `&&` (overlaps)
operators in PostgreSQL. They are useful for GIN-indexed data such as a
`jsonb` or array column.

  [arel-discussion]: https://discuss.rubyonrails.org/t/what-has-happened-to-arel/74383/51