Migrate Test Suite

[naomi-lgbt]

This will likely take multiple PRs, but:

• We should remove the now deprecated discordjs-testing library
• We should convert vitest to use the expect library, not the assert library
• We should use vi.mock() to mock discord.js methods and allow us to reach 100% test coverage.

[a2937]

We should convert vitest to use the expect library, not the assert library

Can you help me verify that it's a good idea to do this? I was part through when I realized some of the expect calls aren't exactly one to one and don't seem to have a way of adding a special message.

For example: https://github.com/freecodecamp/camperchan/blob/1fbe4a2b50fdaa126a8fcb0659ffb49bab3c1c23/test/modules/createLogFile.spec.ts#L17

[naomi-lgbt]

expect(value, "custom message").to.be