OCaml language support

It would be quite beneficial to support also the [OCaml](https://ocaml.org) language, most repositories have the [opam](https://opam.ocaml.org) file with the dependencies specified, see the [syntax](https://opam.ocaml.org/doc/Manual.html#General-syntax) of these opam files.

No repository files, tests, or entry points are named. Start by reviewing how existing language and package-manager support is organized, then consult the linked opam syntax documentation. Done means Dependabot can recognize OCaml repositories and use their opam dependency declarations for updates.

Written by the indexing model from the issue text.