Support YAML and JSONC for resource manifests

[michaeltlombardi]

Summary of the new feature / enhancement

As a DSC Resource author, I want to be able to author and maintain my resource manifests in YAML without needing to convert them to JSON as a build step, because authoring, maintaining, documenting, and reading YAML files is easier for me.

I'd like to be able to author my manifests in either JSONC or YAML so that I can include comments for both local development and maintenance purposes.

Proposed technical implementation details (optional)

Support discovering DSC Resource manifests if they're in the PATH with any of the following file extensions:

• .dsc.resource.json
• .dsc.resource.jsonc
• .dsc.resource.yaml
• .dsc.resource.yml

[SteveL-MSFT]

WG discussed this to allow resource manifest to be in YAML, but not mix of YAML/JSON in a single file.