Resolve "Ligo 0.59.0+ breaks MR 2048 (Make [@annot:] mean no annotation)."

Motivation and Context

[@@annot] was not read by desugaring pass. This problem is solved properly in !2425 (merged)

Description

match on "annot:" and "annot"

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

Fix breakage related to annotated fields with empty string

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).

Closes #1723 (closed)