This refactoring includes the following:
1. Separate backend-neutral part of the metadata printer `Kotlinp`
from the part that accesses JVM-specifics: `JvmKotlinp`.
2. Introduce `org.jetbrains.kotlin.kotlinp.Printer`: The component
that renders both individual `Km*` nodes and the whole metadata
tree, and does so with the proper indentation.
^KT-62340