This PR changes `nu_path::expand_path_with()` to no longer remove
trailing slashes. It also fixes bugs in the current implementation due
to ineffective tests (Fixes#12602).
# Description
This PR adds a fuzzer for the nu-path and the nu-parser crate.
Now you can go to `crates/nu-path/fuzz`/`crates/nu-parser/fuzz` and run `cargo fuzz` to
find crashes.
https://github.com/nushell/nushell/issues/10365 and #9417 was found by
this
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Co-authored-by: sholderbach <sholderbach@users.noreply.github.com>