Convert .ci/ folder to molecule tests

[chrisjsewell]

The .ci/ folder mainly contains scripts and tests that require a "pre-built" environment to run on and/or takes too long to run as part of the "normal" unit tests in tests/.

Its a bit of a mess though and, particularly is not ideal because all the tests are set-up to run on Jenkins or GH actions and are non-trivial to run and develop locally.

On quantum-mobile we use molecule which supports the automated creation/destruction of temporary isolated environments (usually but not restricted to docker containers) and the running of tests therein.
I think it should be possible to restructure this folder into a molecule configuration that could be run both locally and on the required CI platforms (see https://molecule.readthedocs.io/en/latest/ci.html#continuous-integration)

Originally posted by @chrisjsewell in #4548 (comment)

In fact, perhaps it would be possible to replace it with molecule testing. Then it would mean that you could actually run all these tests locally, rather than just via Jenkins/GH actions