[llvm-pdbdump] Merge functionality of graphical and text dumpers.

The *real* difference between these two was that

a) The "graphical" dumper could recurse, while the text one could
   not.
b) The "text" dumper could display nested types and functions,
   while the graphical one could not.

Merge these two so that there is only one dumper that can recurse
arbitrarily deep and optionally display nested types or not.

llvm-svn: 301204