DbView: filter packages by supported/unsupported images/flavours

There are some flavours/images/machines in Oniro that are available to build but are unsupported or only partially supported (see https://git.ostc-eu.org/oss-compliance/epics/-/issues/4), and that require a lower level of audit thoroughness.

The Audit Team should be able to filter packages by support level (information on support level of different images/flavour/machines needs to be added somewhere, to enable this filtering)