[AST] Add individual size info for Types in -print-stats
This mirrors what is done for Decls and Stmts in the -print-stats
output, ie instead of printing "57426 LValueReference types"
we print "57426 LValueReference types, 40 each (2297040 bytes)".
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@339024 91177308-0d34-0410-b5e6-96231b3b80d8