pronouns: accept they/them and they/them/theirs

[half-duplex]

Description

Checks:

• all five provided ("they/them/their/theirs/themselves")
• prefix matches ("they/them[/...]", common)
• subject/object/possessive ("they/them/theirs", common)
• ellipsised ("they/.../themself", for compatibility with sopel 7.0 and pronoun.is)

Also fixes a typo ("eirslef").

Closes #2068
Furthers #2069

< mal> .setpronouns ze
< Sopel> mal: Thanks for telling me! I'll remember you use ze/hir/hir/hirs/hirself. Or, if you meant one of these, please tell me: ze/zir/zir/zirs/zirself
< mal> .setpronouns ze/hir
< Sopel> mal: Thanks for telling me! I'll remember you use ze/hir/hir/hirs/hirself.
< mal> .setpronouns they/.../themself
< Sopel> mal: Thanks for telling me! I'll remember you use they/them/their/theirs/themself.
< mal> .setpronouns they/them/theirs
< Sopel> mal: Thanks for telling me! I'll remember you use they/them/their/theirs/themselves. Or, if you meant one of these, please tell me: they/them/their/theirs/themself

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

[dgw]

I think we'll keep things simple for 7.1 and take #2069. This can go in early 8.0, ideally right before the pronouns plugin gets extracted into a standalone package.

[dgw]

This block is broken now that KNOWN_SETS is a list instead of a dict, btw.

sopel/sopel/modules/pronouns.py

Lines 61 to 64 in 2f05a7d

	for short, set_ in KNOWN_SETS.items():
	if pronouns == set_:
	break
	short = pronouns

[2021-06-30 02:34:50,537] sopel.bot            ERROR    - Unexpected error ('list' object has no attribute 'items') from dgw at 2021-06-30 07:34:50.537146. Message was: ,pronouns dgw
Traceback (most recent call last):
  File "/mnt/c/Users/dgw/github/sopel/sopel/bot.py", line 757, in call_rule
    rule.execute(sopel, trigger)
  File "/mnt/c/Users/dgw/github/sopel/sopel/plugins/rules.py", line 1057, in execute
    exit_code = self._handler(bot, trigger)
  File "/mnt/c/Users/dgw/github/sopel/sopel/modules/pronouns.py", line 76, in pronouns
    say_pronouns(bot, trigger.group(3), pronouns)
  File "/mnt/c/Users/dgw/github/sopel/sopel/modules/pronouns.py", line 91, in say_pronouns
    for short, set_ in bot.memory['pronoun_sets'].items():
AttributeError: 'list' object has no attribute 'items'

[dgw]

Let's just ship this with the conversion back to dict I made. I'll continue tweaking things as I implement the new feature I was working on (based on this branch) when I discovered the .pronouns-breaking regression.