[svn-r22567] HDFFV-7784: add attributes to the list of file contents option for h5dump. This is accomplished by adding an optional value to the option (-n)

Created test and reference files.

Tested: local linux with cmake

tools/testfiles/tpbitsIncomplete.ddl

@@ -2,6 +2,7 @@ usage: h5dump [OPTIONS] files
   OPTIONS
      -h, --help           Print a usage message and exit
      -n, --contents       Print a list of the file contents and exit
+                          Optional value 1 also prints attributes.
      -B, --superblock     Print the content of the super block
      -H, --header         Print the header only; no data is displayed
      -A, --onlyattr       Print the header and value of attributes