Fix bugs with veto files, dangling symlinks and directory delete.

Fix bugs:

https://bugzilla.samba.org/show_bug.cgi?id=14878 https://bugzilla.samba.org/show_bug.cgi?id=14879

Finally adds regression tests to ensure the behavior stays constant with veto files, msdfs links and dangling symlinks.

Passes ci. I made it work with the streams_xattr and xattr_tdb modules :-).