Add Static Scanning Action

[blink1073]

Add an Action that handle Static Scan results. Notionally it will grab all of the dismissed and open alerts for a ref and produce a new SARIF file based on those. For the dismissed ones, I’d use the dismissed_reason in the JSON response from GitHub. We will place the file in the S3_ASSETS folder to be uploaded to the S3 bucket.

[alcaeus]

See #11 for a draft action to export a SARIF report from code scanning alerts.

[blink1073]

Fixed by #11.