add support for filtering candidate repos for import

[scott-es]

In order to operationalize, some snyk administrators will need the ability to filter which repositories this automation will consider for import into Snyk.

The first iteration could filter by repository name which would work well for repos using standardized naming conventions.

Could potentially filter on other metadata about the repository such as github topics or labels if that data is available.

A "jq-style" filter would be flexible enough to both exclude or include candidate repos as needed.