btrfs: print-tree: print information about inode extref items

btrfs: print-tree: print information about inode extref items

Currently we ignore inode extref items, we just print their key, item
offset in the leaf and their size, no information about their content
like the index number, parent inode, name length and name.

Improve on this by printing the index, parent and name length in the same
format as btrfs-progs. Note that we don't print the name, as that would
require some processing and escaping like we do in btrfs-progs, and that
could expose sensitive information for some users in case they share their
dmesg/syslog and it contains a leaf dump. So for now leave names out.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>