peer: introduce a limitedarguments attributes
When set to True, it signal that the peer cannot receive too larges arguments
and that algorithm must adapt. This should only be True for http peer that does
not support argument passed as "post".
This will be useful to unlock better discovery performance in the next
changesets.
I am using a dedicated argument because this is not really a usual
"capabilities" things. An alternative approach would be to adds a
"large-arguments" to all peer, but the http peers. That seemed a bit too hacky
to me.
(binary:application/octet-stream)