use absolute paths for pwd when spawning subprocesses, as relative pa…

…ths don't seem to get properly resolved when passed in here

revert java 17 version change

fixs for multi-path relativization

multi-mapping serializer

mapping-serializer

try and work around OS_LIB_PATH_RELATIVIZER_BASE crash:

Make `os.Path.pathSerializer` configurable via an env var `OS_LIB_PAT…

…H_RELATIVIZER_BASE` (#415)

This makes configuration a lot more reliable than doing it via a
`DynamicVariable`, since it automatically propagates across classloader
and subprocess boundaries

Update WatchServiceWatcher.scala