vfs_default: assert all passed in fsp's and names are non-stream type

vfs_default: assert all passed in fsp's and names are non-stream type

Enforce fsp is a non-stream one in as many VFS operations as possible in
vfs_default. We really need an assert here instead of returning an error, as
otherwise he can have very hard to diagnose bugs.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15126
MR: https://gitlab.com/samba-team/samba/-/merge_requests/2643

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>
Autobuild-User(master): Volker Lendecke <vl@samba.org>
Autobuild-Date(master): Wed Aug 10 16:32:35 UTC 2022 on sn-devel-184

(cherry picked from commit fc45fcfde51b0b0bdcd524c82a0f9eabf7273045)