Refactor config - consolidate and refresh print_table_entry

It's time for print_table_entry to get a bit of refreshment.  The way it
was put together, we needed to maintain the list of known configuration
keys of interest twice, in different shapes.  This is error prone, so
move the list of strings to a common list for all printing cases, and
use simple formatting of lines to do the actual printout based on that
list.

Reviewed-by: Rich Salz <rsalz@openssl.org>