url: fix .title vs url callback plugins

[half-duplex]

• .title for e.g. reddit would say "Sorry, couldn't title that" followed by the reddit.py callback output
• last_seen_url (therefore .title sans args) was missing callback'd/excluded URLs
• tighten some security dumbs (except the safety part in safety: rework #2279)
  • no point in checking ip without DNS lookups if an attacker has $5 and a namecheap account
• add type hints
• some other tidying.

Related for some remaining issues: #2281
Fixes #2054
Fixes #2055

Checklist

• I have read CONTRIBUTING.md
• I can and do license this contribution under the EFLv2
• No issues are reported by make qa (runs make quality and make test)
• I have tested the functionality of the things this change touches

[half-duplex]

RE_DCC - Seems to strip "dcc send". Should this ever matter? DCC is CTCP only, and title responses should never be sent as CTCP, right?

[Exirel]

Given that you are fixing an issues, that's pretty impressive work. I like that every time you work on something, you make it more clear for me and give me better ideas than I had for future refactoring.

So all in all, good job.

[Exirel]

Mostly style nitpicks. All the complains I have about process_urls come from the complexity of the feature that has outgrow the old interface that was put in place (probably by me at some point).

So this is now in my "refactoring" bucket, and clearly not in the near future because, as I already said: this PR is a damn good work.

[Exirel]

Is there a reason for this PR to still be a draft? It looks pretty good to me. Did I forget something?

[half-duplex]

I was going to remove the DCC thing if we can't figure out why it's there, but I guess that's stretching the scope a bit.

[dgw]

I wouldn't mind removing the seemingly useless DCC regex, but I'll merge this regardless of whether that's included by the time I get to its place in the test/review queue.

[dgw]

by the time I get to its place in the test/review queue.

I did. It passed my gauntlet. 🎉