debugfs: Add -p option to ls subcommand.

debugfs: Add -p option to ls subcommand.

Originally submitted by Jason Pyeron:

While working with a compromized system (suckit root kit) hidden files
were viewable by debugfs but not any other utility.  When spaces and
tabs were put into the directory names defugfs did not "show" them.

"ls -p" quotes the output so is can be parsed easily.

Addresses-Red-Hat-Bugzilla: #149480
Addresses-Sourceforge-Feature-Request: #1201667

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>