Add a test to ensure the illustrate the behavior of type-enclosing command showed in issue #1949

[Tim-ats-d]

This PR adds a test to illustrate the issue #1949 opened by Liam.
I don't know if it deserves to be fixed or if it is planned to be fixed but in doublt. What do you think @voodoos?

[xvw]

I think that here, the main issue is that (where the comment is inlay hint:

(* 'a -> 'b -> 'b *) 
let f x y = y

But if you hover y or x, it will be 'a because the type expression is different. So I guess that, since the HoverProvider is in OCaml-LSP, we should probably have a test on OCaml-LSP. (Even I think that this is not something that we can easily fix, or maybe resolving types accros enclosings)