Rewrite of the standard library

Motivation and Context

The standard library needs to be better written and documented.

Description

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

• Added a module Big_set (lazily accessed sets, based on Big_map)
• Documentation for CameLIGO and JsLIGO.
• Introduced local type t aliases in modules Set, List, Map etc.
• Renamed the type parameters for maximum readability.
• Added, when meaningful, functions of_list that can take a list expression that may not be a literal.
• Deprecated some functions and added equivalent ones with a better name (e.g, List.head and List.head_opt).
• Added either a function size or length so all modules have both.
• Same for sub and slice whenever meaningful.
• Added functions empty in all modules.
• Simplified implementations, made them uniform (order of constructors in pattern maching, for example), tried to avoid relying on built-ins.
• The module Option was messy.

Checklist:

• If a new syntax has been introduced, put a message on slack ligo-lsp
• 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).