CameLIGO: add modules inclusion directive

Motivation and Context

Description

This MR adds support for the include directive in structures / top-level.

At the signatures level, it allows to extend and restrict modules as contracts.

module IncDec = struct
  type storage = int
  type return = operation list * storage

  let initial_storage : storage = 42

  [@entry] let increment (delta : int) (store : storage) : return = [], store + delta
  [@entry] let decrement (delta : int) (store : storage) : return = [], store - delta
  [@entry] let reset (() : unit) (_ : storage) : return = [], 0
end

module type IIncOne = sig
  type storage
  type return = operation list * storage

  val initial_storage : storage
  [@entry] val increment : int -> storage -> return
  [@entry] val reset : unit -> storage -> return
  [@entry] val one : unit -> storage -> return
end

module IncOne : IIncOne = struct
  include IncDec

  [@entry] let one (() : unit) (_ : storage) : return = [], 1
end

As it can be seen above, IncOne takes the implementation from IncDec (using include IncDec), implements a new entry point (one), and restricts the signature (i.e. decrement is not an entrypoint of the final contract).

Component

• compiler
• website
• webide
• vscode-plugin
• debugger

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Performance improvement (non-breaking change that improves performance)
• None (change with no changelog)

Changelog

Checklist:

• Changes follow the existing coding style (use dune @fmt to check).
• Tests for the changes have been added (for bug fixes / feature).
• Documentation has been updated.
• Changelog description has been added (if appropriate).
• Start titles under ## Changelog section with #### (if appropriate).
• There is no image or uploaded file in changelog
• Examples in changed behaviour have been added to the changelog (for breaking change / feature).