We would like to use IPC communication during testing, so that we
can leverage indpendent test runs. However, the implementation turned
out to be buggy in the now-unmaintainted `nanomsg`.

Concurrency is a good way to trigger any interleaving bug.

They can be enabled with `GGTX_LOG_LEVEL` during tests.

The bug is elsewhere.

This commit extends the timeout around the `readTChan` in the ping-pong
test to 60 seconds, mostly to account for CI slowness and to rule-out
potential source of flakyness.

The calls to `threadDelay` have been removed, as they doesn't seem to
affect the overall stability of the test (at least locally) -- the
point of the exercise is trying to expose as much as possible potential
problems which might be masked by active waits.

Relax a bit moveChecks to account for shared nodes

Closes #455

See merge request !398

Before we were repeating the same code to initialise all the different
loggers. This commit introduces two stock loggers called `ioStdLogger`
and `monadicStdLogger` which can be reused many times.

It also allows the `GGTX_LOG_LEVEL` to take effect during `readConfig`,
so that the `startupInfo` would show up the correct information.

We can use it to implement the specific case for `serveWorkerAPI`, while
giving the user the ability to do things in the monad `m`, like
introduce specific logging.

Also, remove caddy from docker-compose.

This commit fixes a bug where a user member of a team (but NOT the owner
of such team) couldn't move nodes.

No need to copy .nix files. They are bound by CI anyways.