sopel-plugins CLI cannot manage removed plugins

[dgw]

Requested Feature

I think being able to do e.g. sopel-plugins disable thiswasremoved via the CLI would be helpful.

Problems Solved

After deleting or uninstalling a plugin called name, if one doesn't do it ahead of time, sopel-plugins disable name will display "No plugin named name." and leave the config file untouched.

Alternatives

The alternative (and current workaround) is to manually edit the .cfg file.

Notes

I'm using core.enable on my test bot, so I noticed the inability to disable a removed plugin. There's probably behavior that would be similarly useful for the core.exclude setting (from which plugins are usually removed with sopel-plugins enable, but I haven't spent the time to figure out how that should look yet. (This is already enough non-8.0.0-relevant work for one day!)

[Exirel]

We could have a sopel-plugins prune subcommand to automatically perform that.

[dgw]

There's a thought. Maybe with a Proceed (Y/n)? prompt like you get for pip uninstall.