Refactor version lists

[AMDmi3]

There are version lists on projects, versions_compact and information pages, and these need to be fixed.

• First of all, there should be a single piece code which creates these lists. For now, there are three pieces of code which do the same thing in slighly different ways:
  • packageset_aggregate_by_version
  • iter_aggregate_versions
  • packages_to_summary_items
• It should handle some cases better, for instance recalled and vulnerable status. E.g. if an input list contains 1.2.3, 1.2.3 with recalled flag and 1.2.3 with vulnerable flag, it should merge these into a single 1.2.3 entry with both recalled (Improve recalled status handling #205) and vulnerable flags. Likewise, all places should handle sorting wrt. sink flag and *_is_patch flags equally, and calculate spread correctly.