[Indent] use ocp-indent when ocamlformat is deactivated

[bobot]

Fixes #1792 . If ocamlformat is disable directly use ocp-indent for indentation instead of still trying to parse it.

But no tests have been added.

[bobot]

@gpetiot #1814 could make this PR obsolete, but it could still be useful for outputting better information in disabled case.

[gpetiot]

I think the numeric feature should never be called in emacs if ocamlformat is disabled.
Maybe ocamlformat will be the entry point for ocp-indent in the future but I'm not sure that's where we want to go, so I'm not fond of calling ocp-indent when ocamlformat is disabled.

I'm closing this one for now :)