feat(ocaml): Add OCaml queries

[beajeanm]

I'm a treesitter queries newbie, so I'd appreciate the feedback on these queries.

This is an example of syntactically correct ocaml I used to test them:

let example_function param1 param2 = param1 + param2

class example_object =
  object (self)
    method do_stuff x = raise Not_found
  end

(* This is a comment. *)

let some_loops () =
  for variable = start_value to end_value do
    expression
  done;
  while boolean - condition do
    expression
  done

let conditionals () =
  let if_condition = if a then b else c in
  let match_cases = match a with b -> 1 | c -> 2 in
  let function_expression = function b -> 1 | c -> 2 in
  ()

let test_call =
  (* A function call, followed by 3 arguments. *)
  String.fold (fun a b -> a) 0 xs

let some_blocks =
  let begin_block = begin
    let inner_block = a in
    b
    end
  in
  let paren_block =
    (
      let inner_block = a in
      b
    )
  in c