This introduces a new type p11_list_printer, which abstracts a
pretty-printer for key value pairs, by maintaining the context of the
current printing operation, including indentation and header colors.
Coverage: 69.955% (-0.08%) from 70.033% when pulling c940f50b765ed79bef39898c8739e2d92b7bf1f6 on ueno:wip/dueno/print into 1b14bfa49c1da1f6c6037e6c60f92a76d92a2464 on p11-glue:master.
This introduces a new type p11_list_printer, which abstracts a pretty-printer for key value pairs, by maintaining the context of the current printing operation, including indentation and header colors.