Apply easy fixes/inspections

[mdedetrich]

This PR applies easy inspections/fixes found within Intellij + some others i.e.

• Optimizing/reorganizing imports
• Adding types to public methods (this was skipped in tests since its kind of pointless there)
• Adding types to implicit definitions (this is a requirement in Scala 3 and good practice in general)
• Naming boolean parameters
• Making case class final (case class should really be final by default because overriding a case class can break expected that is expected of a case class)
• Using _ initializer instead of null
• Adding @tailrec for methods which are tail call recursive
• Make traits extend Product and Serializable to make types nicer (see https://stackoverflow.com/a/36526562)

All in all, none of these changes should be that controversial