Convert YAML to Jsonnet

Would love a function to convert YAML (with comments) to Jsonnet. Plugins to convert YAML to JSON already exist, but unfortunately, they drop comments (as they should, because JSON doesn't support them). Additionally, keys are usually quoted, which is unnecessary in Jsonnet.

Start by reviewing how the VS Code extension currently handles YAML-related conversion and how existing YAML-to-JSON plugins treat comments and quoted keys. Define the conversion behavior for preserving comments and emitting Jsonnet syntax, then verify that the resulting output meets both requirements.

Written by the indexing model from the issue text.