Add a consensus parameter for blocking single hop client intro

In #22689 (moved), we allow single hop client intro when the service is multi-hop. But we might want to block it entirely some time in the future.

changed milestone to %Tor: unspecified

added 029-backport-maybe 031-backport-maybe 032-backport-maybe 033-backport-maybe 034-removed-20180328 034-triage-20180328 component::core tor/tor milestone::Tor: unspecified owner::teor parent::17945 points::0.5 priority::medium resolution::duplicate severity::normal status::closed tor-hs tor2web type::enhancement labels

Trac:
Keywords: N/A deleted, 034-triage-20180328 added

Per our triage process, these tickets are pending removal from 0.3.4.

Trac:
Keywords: N/A deleted, 034-removed-20180328 added

These tickets, tagged with 034-removed-*, are no longer in-scope for 0.3.4. We can reconsider any of them, if time permits.

Trac:
Milestone: Tor: 0.3.4.x-final to Tor: unspecified

Let's do this all at once in #22689 (moved)

Trac:
Resolution: N/A to duplicate
Status: assigned to closed

closed

changed time estimate to 4h

moved to tpo/core/tor#25371 (closed)