meson: improve summary() printout

Pass bool_yn kwarg to summary() to make it print boolean arguments as nice coloured YES/NO instead of true/false.

We can also pass multiple arguments like a bool and a disabled_reason string. In meson 0.54 these can be printed on one line if we set the line_sep kwarg. In meson 0.53 these will always be printed on two lines (and it will warn about the line_sep arg), so only pass two args if docs are disabled and otherwise just pass one arg, so we don't end up with an ugly empty line with meson 0.53.