MINOR: tools: start to distinguish stream and dgram in str2sa_range()

MINOR: tools: start to distinguish stream and dgram in str2sa_range()

The parser now supports a socket type for the control layer and a possible
other one for the transport layer. Usually they are the same except for
protocols like QUIC which will provide a stream transport layer based on
a datagram control layer. The default types are preset based on the caller's
expectations, and may be refined using "stream+" and "dgram+" prefixes.

For now they were not added to the docuemntation because other changes
will probably happen around UDP as well. It is conceivable that "tcpv4@"
or "udpv6@" will appear later as aliases for "stream+ipv4" or "dgram+ipv6".