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Use qubit-index newtypes in Rust space (#10761)

* Use qubit-index newtypes in Rust space

This converts all of our Rust-space components that are concerned with
virtual and physical qubits (via the `NLayout` class) to represent those
integers with newtypes wrapping them as half-size indices, and changes
the `NLayout` API to only allow access via these types and not by raw
integers.

The way this is done should have no overhead in time usage from Rust,
and is actually a reduction in memory usage because all the qubits are
stored at half the width they were previously (for most systems).  This
is done to add type safety to all our components that were concerned
with the mixing of these two qubits.  The implementation of this commit
already turned up the logical bug fixed by gh-10756.

* Separate out type-safe enforcement in `NeighborTable` to another commit

This reverts the changes to the coupling-map generation and the indexing
into `NeighborTable` that were designed to make it more type safe in
favour of doing that in a separate commit.

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