QoL improvements to our testing framework

[matthewbastien]

Description

Add a new tag() function that can be used to add three different tags to tests or suites:

• small: Used mainly for unit tests. (2 second timeout)
• medium: Used for most integration tests. (2 minute timeout)
• large: Used for long running tests that will run only in Nightly test runs. (10 minute timeout)

When tagging a suite all child suites and tests will inherit the same tag(s) unless otherwise specified. For example:

tag("medium").suite("A suite that contains medium sized tests by default", () => {
    tag("large").test("Explicitly applies the large tag to the test", () => {
        // timeout: 10 minutes
    });

    test("Inherits the default tag of medium from the suite", () => {
        // timeout: 2 minutes
    });

    suite("All tests in this suite will also inherit the medium tag", () => {
        // timeout: 2 minutes
    });
});

The large tag replaces the @slow label that we used to add to all of our nightly-only tests.

I've also added a couple other QoL improvements:

• Imports will now be sorted using Prettier to keep imports consistent between all files.
• Tests can now import sources using @src instead of having to do ../../../../src.

Tasks

• Required tests have been written
• [ ] Documentation has been updated
• [ ] Added an entry to CHANGELOG.md if applicable