Convert vuln-list ingestion to worker handler

Convert the vuln-list ingestion component into a worker handler.

This component is a worker handler. See the worker design for additional information.

Diagrams

sequenceDiagram

    participant s as Scheduler
    participant w as Worker
    participant tr as Trivy Ingest Handler
    participant db as SQL
    participant ps as PubSub
    participant remote as Trivy Vuln-List Repo

    s ->> ps: Trigger Trivy Ingestion

    ps ->> w: Poll for Message
    w ->> tr: Run

    tr ->> db: Get configuration and state

    tr ->> remote: Clone or Pull
    tr ->> tr: Identify changes

    loop Foreach Change
        tr ->> tr: Process change
    end

    tr ->> db: Update state