Stdlib: introducing `Tezos.Next` module and `Assert`

Motivation and Context

Related Issue: #3122

Description

This MR introduces a couple of changes in the stdlib:

• Introduces Tezos.Next
• Introduces Assert
• Introduces Tuple2
• Adds deprecation messages

We do not use include to avoid current problems with this keyword.

As a side-change, we also fix an error related to the signature of or/xor.

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

New factorization on certain components of the stdlib have been introduced:

• A new version of Tezos module/namespace, which is accessible as Tezos.Next.
• Grouped commands dealing with assertions in Assert module/namespace.
• Grouped commands dealing with binary tuples in Tuple2 (including curry/uncurry).

(see the documentation on each module/namespace of the API for further information)

Warning messages signaling to use these new variants have been added to the old functions.

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).