Bump go-diskfs to v1.9.4, which contains diskfs/go-diskfs#413 handling
squashfs images that have no fragment table or no xattr table. On v1.9.3
these images fail to list at all (ReadDir errors, or a nil xattr-table
dereference inside the library).
Adapt the backend to the v1.9.4 io/fs API: ReadDir now returns
io/fs.DirEntry (metadata via DirEntry.Info), and files are opened via
FileSystem.OpenFile instead of the removed FileStat.Open. The path
conversion added in c10eb47 (toIOFS) is reused.
Add a regression test with two committed fixtures built from trivial
placeholder content: an empty directory (no fragment table) and a small
tree whose superblock has the NO_XATTRS flag set while inodes still carry
an xattr index.
Fixes#9004
maximilizeandNick Craig-Wood
2f3895fa3c