plugins.rules: URLCallback shall handle invalid URLs by ignoring them

[dgw]

Description

Invalid URLs can crash Sopel's URL handling, as reported on IRC by @RhinosF1. The traceback is included below for reference.

We handle it now by simply skipping any URL that causes the underlying library (urllib.parse from Python's standard library) to throw a ValueError when plugins.rules.URLCallback.match() tries to determine its scheme.

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

Notes

Includes a new test verifying the behavior—and more importantly, the lack of an exception being thrown.

Also fixes an incorrect classname in one of the other URLCallback tests, in a separate commit.

Motivating traceback, reported on IRC

[2021-06-05 10:03:52,811] sopel.exceptions     ERROR    - Fatal error in core, handle_error() was called.
Buffer:

Last Line:
@account=mirahezebots :MirahezeRC!~MirahezeR@miraheze/bots PRIVMSG #miraheze-feed :famepediawiki 5* 14[[07Yasir Tech14]]4 !N10 02https://en.famepedia.org/w/index.php?oldid=35752&rcid=23962 5* 03YasirTech 5* (+6564) 10Created page with "{{Short description}}'''Yasir Tech''' '''(یاسر ٹیک)(यासिर टेक) [https://yasirtech.com]is an Blogger, He was born on 01 January 2009 in Firozpur in Sambh..."
[2021-06-05 10:03:52,812] sopel.exceptions     ERROR    - Fatal error traceback
Traceback (most recent call last):
  File "/usr/lib/python3.7/asyncore.py", line 83, in read
    obj.handle_read_event()
  File "/usr/lib/python3.7/asyncore.py", line 422, in handle_read_event
    self.handle_read()
  File "/usr/lib/python3.7/asynchat.py", line 171, in handle_read
    self.found_terminator()
  File "/srv/sopelbots/prodvenv/lib/python3.7/site-packages/sopel/irc/backends.py", line 241, in found_terminator
    self.bot.on_message(line)
  File "/srv/sopelbots/prodvenv/lib/python3.7/site-packages/sopel/irc/__init__.py", line 228, in on_message
    self.dispatch(pretrigger)
  File "/srv/sopelbots/prodvenv/lib/python3.7/site-packages/sopel/bot.py", line 901, in dispatch
    for rule, match in self._rules_manager.get_triggered_rules(self, pretrigger):
  File "/srv/sopelbots/prodvenv/lib/python3.7/site-packages/sopel/plugins/rules.py", line 440, in get_triggered_rules
    return tuple(sorted(matches, key=lambda x: x[0].priority_scale))
  File "/srv/sopelbots/prodvenv/lib/python3.7/site-packages/sopel/plugins/rules.py", line 431, in <genexpr>
    for match in rule.match(bot, pretrigger)
  File "/srv/sopelbots/prodvenv/lib/python3.7/site-packages/sopel/plugins/rules.py", line 1688, in match
    for url in urls:
  File "/srv/sopelbots/prodvenv/lib/python3.7/site-packages/sopel/plugins/rules.py", line 1684, in <genexpr>
    if urlparse(url).scheme in self._schemes
  File "/usr/lib/python3.7/urllib/parse.py", line 368, in urlparse
    splitresult = urlsplit(url, scheme, allow_fragments)
  File "/usr/lib/python3.7/urllib/parse.py", line 459, in urlsplit
    raise ValueError("Invalid IPv6 URL")
ValueError: Invalid IPv6 URL
[2021-06-05 10:03:52,897] sopel.exceptions     ERROR    - ----------------------------------------

[Exirel]

Nice test you got here.