[#1658] Support configuration: part 2

Motivation and Context

Related issues

Resolves #1658 (closed).

✅ Checklist for the LIGO Language Server

• I checked whether I need to update the README.md file for the plugin and did so if necessary
• I checked that my changes work in Emacs, Vim, and Visual Studio Code
• (Before merging) The commit history is squashed and prettified, and follows the Serokell commit policy, or the MR is set to squash the commits

Description

This MR finishes the work needed to finish reading a configuration from Visual Studio Code. See the changelog for more details on what was changed.

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

The LIGO Language Server now supports a few new changes and fixes related to configuration, notably:

• It's now possible to disable specific features from the Visual Studio Code extension. Check the README for more details.
• Fixed an exception that would be thrown when using the language server with Emacs related to decoding null from the configuration.
• The language server now respects Deprecated from the Visual Studio Code configuration and emits a warning when opening a PascaLIGO file if that is not set.
• Configuration changes may now be done dynamically. Previously, a language server restart would be required for changes to take effect.

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).