6139: Make find_path_prefixed configurable r=matklad a=Veykril
This makes `find_path_prefixed` more configurable allowing one to choose whether it always returns absolute paths, self-prefixed paths or to ignore local imports when building the path.
The config names are just thrown in here, taking better names if they exist :)
This should fix#6131 as well?
Co-authored-by: Lukas Wirth <lukastw97@gmail.com>