MINOR: listener: detect stream vs dgram conflict during parsing

MINOR: listener: detect stream vs dgram conflict during parsing

Now that we have a function to parse all bind keywords, and that we
know what types of sock-level and xprt-level protocols a bind_conf
is using, it's easier to centralize the check for stream vs dgram
conflict by putting it directly at the end of the args parser. This
way it also works for peers, provides better precision in the report,
and will also allow to validate transport layers. The check was even
extended to detect inconsistencies between xprt layer (which were not
covered before). It can even detect that there are two incompatible
"bind" lines in a single peers section.