fix(output): ensure that vulnerabilities are sorted by ID across groups in table output (#1598)

While prototyping some changes to help with #1567, I discovered that the
table output format is not explicitly sorting vulnerabilities across
their groups, meaning we're assumingly using the order that the API
gives us, and means our current output does not actually follow a
predictable order.

To address this, I've modified the table outputter to sort vulnerability
groups by the first ID in each group as a group by definition will
always have at least one ID and the first ID should be the one primary
one since we already sort ids within each group as part of building the
general results

Author: G-Rath