Instead of the caller having to deal with it in each instance.

We replace the onion keyserver we actually use in Tails with an onion
server we run on Chutney, that redirects all TCP traffic to a clearnet
keyserver.

Will-fix: #12211

It can be reconfigured to point to any clearnet TCP host and port.

Any way, the missing `-i` option made it into a NOP.

This will just make things simpler. So long, real Tor network, and
thanks for all the fish! :)

We now set up all bridges (from now on that term also includes PTs)
using Chutney, so we no longer need to provide them in our "secret"
local configuration any more, which is a big plus in itself.

This includes replacing one of the authorities with a bridge
authority.

Note: the firewall test (i.e. that only the expected hosts are
contacted) is pretty broken at the moment, definitely in the bridge
mode case, but perhaps in normal operation too, since what we check is
which hosts are contacted, and the complete Tor network *and* bridges
now run on the same host (and IP address).

... and make the network definition Git diff friendly.

See the added comment for details.

... provided by Chutney (https://gitweb.torproject.org/chutney.git).
This is enabled iff the local configuration contains something like:

  Chutney:
    src_dir: "/path/to/chutney-src-tree"

otherwise we'll use the real Tor network as we done previously.

The main motivation here is improved robustness -- since the "Tor
network" we now use will exit from the host running the automated test
suite, we won't have to deal with Tor network blocking. Performance
should also be improved.

Will-fix: #9521