Add yaml validator for file configuration

• Ability to specify schema as a comment in the YAML file
• Possible to import JSON Schema for YML validation in VSCode?
• How VSCode does JSON config file validation?

JSONSchema

• Get Options types for properties from flags (CommanderJS convention)
  • Not a type by convention
  • Only types are boolean and string
  • YAML Number should be validated as string
• Variadic options are arrays
  • And for arguments ?
• JSON Schema generation as a util