Consider allowing triage-serverless to use gitlab-triage policy files for real-time triaging

Since we already have policy files in the triage-ops project, it would be awesome to reuse these policy files in this project so that we can run the exact same (hygiene) policies, but in real time!

Ideas for implementation

• The "fetching resources via the API" part of gitlab-triage would not be needed since we're directly receiving a resource via the webhook.
• The "conditions" part of the policy would need to be reimplemented in this project, to be checked against the webhook's payload.
• The "actions" part of the policy could ideally be reused.