daemon/proxyv2: fix client TCP/TLS + merge state structs
Firstly, this adds a missing assignment of comm->proxy
, which would
cause the resolver not to know that a client asked via TCP/TLS, if the
proxy also asked via TCP/TLS.
Secondly, it merges struct pl_proxyv2_sess_data
and
struct pl_proxyv2_iter_data
into a single struct pl_proxyv2_state
,
since they were practically the same. And it adds a bit of documentation
to the struct.