ShellPkg: Update "ls" command to better handle "-r" parameter

This makes sure that recursion into sub directories looks through all subdirectories, not just those that match the initial search pass.  Also only prints out any information for directories in which at least one matching file is found.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jaben Carsey <Jaben.Carsey@intel.com>
Reviewed-by: Erik Bjorge <erik.c.bjorge@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15250 6f19259b-4bc3-4df7-8a09-765794883524