Fixed transpilation of "True", "False" and "Unit".

Motivation and Context

The CST-to-CST transpilation from PascaLIGO to JsLIGO was incorrect on values for the predefined data constructors True, False and Unit. With this MR we transpile

const _ = case x of [True -> 0 | False -> 1]
const _ = case y of [A -> True | B -> False]

into

const _ = match(x, { True: () => 0, False: () => 1 });

const _ = match(y, { A: () => true, B: () => false });

The boolean values in patterns remain unchanged (True and False) because of technical difficulties in the pipeline. We argue that matching on those values is bad style, as a conditional is best. Moreover, we do not have deep pattern matching is JsLIGO, so conditionals should be the obvious choice.

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

Fixed transpilation from PascaLIGO to JsLIGO of predefined data constructors "True", "False" and "Unit" as values (patterns remain unchanged).

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).