Add test for checking the line length of --help output

Add test for checking the line length of --help output

There was some discussion what the line length should be.  Most output
currently clearly targets around 80 columns, but the maximum in use
currently is 95, so we set that as the current maximum.  This just
ensures that there is some guidance and there are no wild deviations.

based on patch by Atsushi Torikoshi <torikoshia@oss.nttdata.com>

Discussion: https://www.postgresql.org/message-id/flat/50ca8ff35a8dd8f9ec89963b503571a7@oss.nttdata.com