Fix all swiftlint warnings

[younata]

Noticed we're having quite a large amount of SwiftLint errors. This addresses all of them.

Checklist - While not every PR needs it, new features should consider this list:

• [ ] Does this have tests?
• [ ] Does this have documentation?
• [ ] Does this break the public API (Requires major version bump)?
• [ ] Is this a new feature (Requires minor version bump)?