This boilerplate creates some basic AprilBot functionality for
connecting to slack and handling some basic types of interactions.

I had to create types for the event handlers for now, though I opened an
issue in the Slack sdk in the hopes they might add types [1] to their
events.

This also swaps out the class-methods-use-this lint rule for a smarter
variety, which is probably something that the upstream maintainer should
consider adding as well [2].

[1] slackapi/node-slack-sdk#1768
[2] iamturns/eslint-config-airbnb-typescript#344

By default, this does not deviate in behavior from the original rule.
It does, however, provide users with additional configuration options
to disable errors when `this` is not used in classes that
implement interfaces or methods that explicitly override parent methods.

The configuration we provide has been left at the default, though,
since those rules are arguably over-permissive in the pursuit of not
requiring type information.

Closes iamturns#344.

By default, this does not deviate in behavior from the original rule.
It does, however, provide users with additional configuration options
to disable errors when `this` is not used in classes that
implement interfaces or methods that explicitly override parent methods.

The configuration we provide has been left at the default, though,
since those rules are arguably over-permissive in the pursuit of not
requiring type information.

Closes iamturns#344.