test: test_tools's mocks are obsolete

[Exirel]

This PR makes test_tools's mocks obsolete, adding deprecation warning on MockConfig, MockSopel, and MockSopelWrapper - replaced by the configfactory fixture, the botfactory fixture, and by the sopel.bot.SopelWrapper class respectively.

As far as I'm concerned, Sopel's codebase doesn't use MockSopel nor MockConfig, making sure that no part of Sopel assumes ~/.sopel/ as the homedir. We may close issue #946 once this is merged.

[dgw]

I'm not a huge fan of needing to put $nickname: into every example that uses bot.reply(). 🙁

Dropping test_tools without warning isn't entirely safe, FYI. It's not in the API docs, but it is referenced in our help tutorial. That's basically "documented", and a quick code search of GitHub for "sopel test_tools" shows a number of third-party packages that use our test tools for their own plugin tests.

[Exirel]

Ok, I'll do two thing:

• be more flexible with $nickname (and revert my changes about that)
• add some deprecation warnings here and there

And I think we'll be good to go. As mentioned on IRC, internal plugins will become externals by Sopel 8.0, and we have a year to craft better testing tools. I'll remember that:

09:45:20 <+dgw> (I would love a testing framework that just auto-tests plugins without having to do the __name__ == 'main' crap though :D)

[Exirel]

@dgw and done! It's way easier to review now I think.

[dgw]

Minor things. Deprecating the Mock* classes is a natural thing to do after making the "real" objects testable directly. We can keep the discussion going about how to test say() vs. reply() in a backwards-compatible way, if you like. 😸

[dgw]

Squash what you're gonna squash, @Exirel.

[dgw]

@Exirel Oh wait, this still has a "post-review fix" commit that should be squashed out before merge. I guess you can take care of that and glance at #1777 at the same time. 😁

[Exirel]

lol

[Exirel]

Done.