CLI scaffolding for YAMLValidator

[abaskk-msft]

Problem

N/A

Solution

N/A

Changes

• Adds the initial CLI scaffolding and verification for the YAML validator, which for now, only verifies file extemsions and validates the files and directories exists.
• The added command includes the validate CLI command, flags include:
  • required --path a path to a .yaml or folder of .yaml files
  • optional --schema a path to a local schema .json file, or a default one if it is not passed in.

Testing

• For now only manual tests were done to verify input filepaths, these tests included
  1. No parameters passed to cli
  2. Validate command without parameters
  3. Validate command with an invalid and valid file path
  4. Validate command with an invalid and valid folder path
  5. Path option input validation to check at least 1 .yaml file exists in a folder
  6. Path option input validation to check Verification that a file has .yaml extension
  7. Check that schema path option input exists in the file system and is a .json file.
  8. Also note, windows wont allow a file and folders with the same name to exist in a path, so this case was ignored
• Perhaps later, tests for this project can be made an run in a new project called YAMLValidator.Tests

[mizrael]

I'd recommend writing some unit tests before merging into master. The cases outlined in the PR description should be ok for now