Unit tests, wires, and endianness

[WrathfulSpatula]

This PR fixes wire map parsing and "endianness" conventions. It also adds a full suite of unit tests for the Catalyst Qrack device back end.

[vprusso]

Hmm, it looks like we have some failing unit tests here: https://github.com/unitaryfund/pennylane-qrack/actions/runs/9374095130/job/25809366794?pr=6

[WrathfulSpatula]

Hmm, it looks like we have some failing unit tests here: https://github.com/unitaryfund/pennylane-qrack/actions/runs/9374095130/job/25809366794?pr=6

@vprusso I think it's due to OpenCL-detection problems (where the CI has no GPU). The last commit attempts to address it.

[WrathfulSpatula]

So, there was also the issue I mentioned, which should now be fixed, but the other problem is the version of catalyst against which we interface and statically link.

All unit tests pass locally, with the v0.7 release of Catalyst. The (other) problem seems to be that I never finished implementing Catalyst installation from source in the Git workflow for unit tests.

[WrathfulSpatula]

Here's the problem: I think we need v0.7 of Catalyst. This is on head of main branch of Catalyst. However, there's no feasibility to building Catalyst from source on CI/CD.

Unfortunately, the CI just has to fail, for now. This should likely be fixed when Catalyst v0.7 is released. Anyone reviewing can test, the unit tests will pass, running locally.

[WrathfulSpatula]

I have also verified, locally, that I receive the same test failures if I check out the v0.6 tag commit of Catalyst and build and install it. There's no way around this: it seems we need the v0.7 release.