Replace dropped `package objects` with top-level definitions

[MateuszKowalewski]

Please see: https://docs.scala-lang.org/scala3/reference/dropped-features/package-objects.html for motivation.

Drive-by commit while I'm reading code… :smile:

[MateuszKowalewski]

The diff here on GitHub looks quite messed up. But that's obviously an issue with the diff algo.

I didn't change anything besides removing the package objects and unindenting the code!

Tests run successfully (of course).

[TomasMikula]

Thanks for the cleanup! I got a reasonably looking diff here on github after checking "Hide whitespace":

[TomasMikula]

Another Scala 2 remnant that comes to mind is using implicits instead of givens. I use givens in all new code, but there's a lot of implicits left.