Mimic fsspec behavior when parsing file:// URLs
File URLs like
file://a
were being parsed in parse_store_url with a path like
ParsedStoreUrl(..., path="")
instead of
ParsedStoreUrl(..., path="./a")
which is the behavior in fsspec. This also makes resolves the parsed
paths to their absolute representation immediately, to prevent eventual
changes in CWD from affecting the resolution of the path later.