[Hacktoberfest Platform/DevOps] Add YAML Lint CI to Shared Actions

[joyliu-q]

When editing the shared-action GitHub workflows, we want to make sure the YAML we are writing are not broken. It would be unfortunate to merge an invalid react.yaml to shared-actions (e.g. with period accidentally added) and cause every product's CI to break.

To resolve this, we need to add some CI that tests the GitHub workflows (e.g. using a yaml linter) for all code pushes. For reference, you can check cdk_validate_manifests for each repo to see how validation is currently done.