refactor: moved send.js file to testing folder

I was trying to create a testing suite based on a comment in send.js about how it should be deleted because it's just for testing. However, currently, our backend is not in a good enough state that testing is really viable.

It turns out that the entire send.js file is more or less just to see how RabbitMQ works, and so I think it should be retained for now for when we will be trying to figure out RabbitMQ, but it will likely not be necessary later.

Related to issue #15 (closed)