config: Catch missing Bridge for ClientTransportPlugin

First of all, tor doesn't support multiple transport name on a single
*TransportPlugin line so get rid of that. The manpage has never documented
that feature and it complexifies the line for no reason. A user can just use
multiple ClientTransportPlugin line instead.

Second, if no Bridge line is found, error immediately and exit. Don't leave
the Bridge line alone there leading to bugs like #25528

Third, when making sure we have a Bridge line with a ClientTransportPlugin, we
now check at the managed proxy list. In order to pull this off, the transport
name had to be added to the managed_proxy_t object so we can match for which
transport it is used for. And thus justifying the removal of multiple
transport support which adds no benefit except complexity.

Fixes #40106

Signed-off-by: David Goulet <dgoulet@torproject.org>
10 jobs for ticket40106_045_01 in 71 minutes and 5 seconds (queued for 7 seconds)
latest
Status Job ID Name Coverage
  Test
passed #6185
debian-disable-dirauth

00:05:26

passed #6186
debian-disable-relay

00:11:14

passed #6181
debian-distcheck

00:11:37

passed #6182
debian-docs

00:09:41

passed #6223
debian-hardened

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passed #6183
debian-integration

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passed #6179
debian-minimal

00:12:09

passed #6187
debian-nss

00:09:46

passed #6184
debian-tracing

00:13:30

failed #6180
debian-hardened

00:16:37