Validate params types in linter

[ChloePlanet]

Please do not post any internal, closed source snippets on this public issue tracker!

Purpose

Output warnings when there's type which is not defined.

e.g.

MobileApp:
  Name:
    return ok <: str                # `str` not found, possible primitive Sysl type: [`string`]
  Login(input <: Servr.LoginData):  # `Servr.LoginData` not found
    return ok <: string
Server:
  !type LoginData:
    userID <: string