Conventionally `bin` folder is home to scripts that are meant to be run by developers working on the project, whereas the `exe` folder is used for executables that are meant to be exported by the gem.
The guidance from the Bundler team around this has been live since 2015: https://bundler.io/blog/2015/03/20/moving-bins-to-exe.html
This PR simplifies the gemspec and updates the `bin` folder to `exe` in the gemspec and removes some of the unnecessarily cleanup that was introduced previously.
