[#1652] Implement prepare rename request

Motivation and Context

Resolves #1652 (closed)

Description

Implements prepare rename. This displays to the user that some lexemes cannot be renamed (like built-in types or keywords).

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

Implements the prepare rename request from the LSP specification. It checks the validity of a rename so that users won't get a prompt for renaming lexemes such as a keyword (like let) or a built-in identifier (like int).

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).