cargo fmt + require cargo fmt to pass in CI

[sam0x17]

• fixes a bunch of trailing whitespace errors so cargo fmt can run
• runs cargo fmt (apparently for the first time ever 😆)
• requires cargo fmt --check to pass in CI from now on
• now runs cargo test --workspace instead of just cargo test --tests which would only run integration tests
• requires cargo check --workspace to pass in CI from now on (this will ensure non-test build succeeds without any errors) removed because CI was running out of disk space 🤣

update: going to keep cargo check --workspace out for now because it just adds to build time and we don't have parallel actions set up for the different steps, will do that in a later pr 👍🏻