Smoke / e2e testing for the bot

[narze]

To make sure that the bot is working, by running Github Actions to check that the bot can at least connect to a server and send simple commands.

What's needed

• A test server and test discord token is needed for the testing
• Setup Corde (I haven't tried this btw, but should be easier than setting up from scratch or mocking Discordjs)

[narze]

I tried Corde and it does not work at all with modern typescript, but the idea is to setup another bot to simulate the user, maybe it's not that hard to do so I may come up with a simple one then...

[narze]

#116