Add Dict module to the testing CI

[cjduncana]

This MR adds a command for testing the Dict module in the CI. I also added an example of how to use Dict.update with instructions on how to add and view said comments.

[cjduncana]

Dict.update in the Standard Library page with the updated comment:

[cjduncana]

I want to figure out how to test a whole directory instead of per file.

[ayazhafiz]

@cjduncana to test a whole directory instead of just a file, we'll need to modify the compiler's loading mechanism to support processing a whole directory at a time in test mode - I'm happy to chat through how to do this if you're interested on the Zulip thread you started, but fair warning, it might be a lot of work 😅 Otherwise, we can file an issue for it

[cjduncana]

Zulip topic referred above.