Instead of requiring the consumer to provide a list of all events which
they wish to handle, we can give them to option of dynamically detecting
them, by scanning the listener's public methods.

This approach is similar to that used by Minitest (scanning for `test_`
methods) and Rails generators (running all public methods in the order
they are defined).

While this is slower than specifying a hard coded list, the penalty is
only during registration. There is no change the the behaviour of
dispatching the events.

https://github.com/ruby/prism/commit/781ebed743