Support the generalization of basis state preparation and the facade legacy device for MPI LGPU

[maliasadi]

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Context:

• PR https://github.com/PennyLaneAI/pennylane/pull/6021 removed code duplication for BasisEmbedding and BasisState. As the result BasisState no longer decomposes to BasisStatePreparation. This PR updates Python unit tests to support this generalization of basis state preparation.

• PR https://github.com/PennyLaneAI/pennylane/pull/6046 added a facade wrapper class for "legacy" devices. This PR is a follow up to PR #839 updating Multi-GPU LGPU device and tests.

Description of the Change:

Benefits:

Possible Drawbacks:

Related GitHub Issues: [sc-71917]

[github-actions[bot]]

Hello. You may have forgotten to update the changelog! Please edit .github/CHANGELOG.md with:

• A one-to-two sentence description of the change. You may include a small working example for new features.
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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 81.50%. Comparing base (4b79587) to head (8e117ff). Report is 2 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #864 +/- ## =========================================== - Coverage 91.77% 81.50% -10.28% =========================================== Files 114 17 -97 Lines 18254 1946 -16308 =========================================== - Hits 16752 1586 -15166 + Misses 1502 360 -1142 ```

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[maliasadi]

@multiphaseCFD there are more things to fix in latest/latest :grimacing: I'll update the changelog right after getting latest/latest :green_circle:

[maliasadi]

@multiphaseCFD latest/latest :green_circle: :tada:

[maliasadi]

@vincentmr I've run them manually! But let's trigger them here too :+1: