- Collapse 3 different loops into one.
- Check all saved stanza ids in the parsed attrs, not just the archive id
- Remove check for archive id in converse-mam since it just duplicates what's now being done in converse-chat
- Don't use disco to check for support, XEP-359 mandates that services SHOULD advertise support,
  which is not a strong enough guarantee that they do.

updates #1856