This commit updates the YAML schema to permit explicitly setting
`recommend: null` or `recommend: ~` in scripts within collection files.
Previously, the schema only allowed string values for the recommendation
field, restricting it to 'standard' or 'strict'. By introducing the
`RecommendationLevel` definition, the schema now supports both string
and null values, providing more flexibility in specifying
recommendations in collection YAML files.
This commit improves collection file editing and error detection
directly in the IDE. It adds YAML schema, IDE configuration and
automatic tests to validate it.
- Introduce a YAML schema for collection file.
- Use `yaml-language-server` for enhanced YAML support in VSCode.
- Add telemetry disabling in `configure_vscode.py` to respect user
privacy.
- Add automated checks to validate YAML file structure against the
schema.
- Remove unused properties and do not allow them in compiler.
