Instead of directly writing the destination file, use the combination of
a `.tmp` suffix and `os.replace` to guarantee that the destination file
is written whole and not partially.
Make the cache directory logic uniform in Python and C++, move the
respective implementations under support since it's project-wide logic
and not exclusive to debug-info.
Package revng's python code in two wheels: `revng` and `revng_internal`.
The revng wheel contains the
`revng.{pipeline_description,model,tupletree}` modules, while the
`revng_internal` one everything under `revng.internal`.
Giacomo Vercesi