Add chutney hs-ipv6 target to tor's test-network-all
This target tests:
- IPv6-only client bootstrap (with the workaround from legacy/trac#19608 (moved))
- IPv6-only HS bootstrap
- IPv4 and IPv6 client to IPv6 HS transmission
I'd like to get this in 0.2.9 - legacy/trac#19608 (moved) slipped through because we didn't have tests like these.