TODOs:
- [x] wait and see if test `1` works;
- [x] ~think of whether we need remaining tests.~ I think we should keep
it - will try to revive and update it

Fixes https://github.com/paritytech/polkadot-sdk/issues/3999

---------

Co-authored-by: Branislav Kontur <[email protected]>

Related to https://github.com/paritytech/polkadot-sdk/issues/3400

Moving all bridges testing "framework" files under one folder in order
to be able to download the entire folder when we want to add tests in
other repos

No significant functional changes

Related to https://github.com/paritytech/polkadot-sdk/issues/3242

Related to https://github.com/paritytech/polkadot-sdk/issues/3176

This PR only adds the first bridge zombienet test back to the CI after
fixing it, reverting
https://github.com/paritytech/polkadot-sdk/pull/3071

Credits to @svyatonik for building all the CI infrastructure around
this.

closes https://github.com/paritytech/parity-bridges-common/issues/2796

This partially reverts the #2439 - there are some changes (unrelated to
CI) that we still want to keep. The reason of that removal is that with
async backing enabled for Rococo AH (and for other chains in the near
future), we see a lot of issues there (because we run `14` nodes +
additional standalone process within a same container and it causes a
lot of timeouts). There's no way known to me to fix it right now, so
we're removing those tests hopefully temporarily to keep CI green

Brridges zombienet tests are non-standard - zombienet currently missing
multiple relay chains support (see e.g.
https://github.com/paritytech/zombienet/pull/796), so we need to go live
with two relay networks, their parachains + custom test runner (which
e.g. doesn't shutdown net when its tests are finished and instead waits
for both networks tests to complete). So we are stuck with native
zombienet provider => this PR is an attempt to gather everything in a
single docker container and run tests there ~Draft, because it is far
from finishing - what I want now is to see how it works on CI~