Add ContractIdleWiresInControlFlow optimisation pass

[jakelishman]

Summary

This transpiler pass removes data dependencies on idle qubits from control-flow operations. For example, given a circuit such as::

from qiskit.circuit import QuantumCircuit

qc = QuantumCircuit(1, 1)
qc.x(0)
with qc.if_test((qc.clbits[0], True)):
    qc.x(0)
    qc.x(0)
qc.x(0)

the current optimisation passes will collapse the inner control-flow block to the identity, but the qubit dependency will remain, preventing the outer two X gates from being cancelled. This pass removes the now-spurious dependency, making it possible to detect and remove the two X gates in a follow-up loop iteration.

As an accidental side-effect of their algorithms, the control-flow-aware routing passes currently do this when they run. This aims to move the logic into a suitable place to run before routing (so the spurious dependency never arises in routing in the first place) and in the low-level optimisation stage.

The aim of this pass is also to centralise the logic, so when the addition of the new box scope with different semantics around whether a wire is truly idle in the box or not, the routers aren't accidentally breaking them, and it's clearer when the modifications happen.

Details and comments

Built on top of #13774, since it's very convenient to have that method for writing the tests. This is one part of #13768.

I haven't hooked this up to the preset pass-managers in this commit; I wanted to do that after #13768 is fixed properly and potentially once box itself has landed.

[qiskit-bot]

One or more of the following people are relevant to this code:

• @Qiskit/terra-core

[coveralls]

Pull Request Test Coverage Report for Build 13419299916

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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Details

• 49 of 49 (100.0%) changed or added relevant lines in 1 file are covered.
• 1958 unchanged lines in 64 files lost coverage.
• Overall coverage decreased (-0.6%) to 88.114%

---

Files with Coverage Reduction	New Missed Lines	%
crates/accelerate/src/euler_one_qubit_decomposer.rs	1	91.5%
crates/accelerate/src/gate_direction.rs	1	97.34%
crates/accelerate/src/target_transpiler/nullable_index_map.rs	1	67.17%
crates/accelerate/src/twirling.rs	1	97.62%
crates/qasm2/src/expr.rs	1	94.23%
qiskit/circuit/add_control.py	1	97.78%
qiskit/providers/basic_provider/basic_simulator.py	1	96.99%
qiskit/providers/fake_provider/fake_openpulse_3q.py	1	92.86%
qiskit/providers/models/backendproperties.py	1	94.74%
qiskit/pulse/calibration_entries.py	1	90.57%

Totals
Change from base Build 13154732632:	-0.6%
Covered Lines:	78405
Relevant Lines:	88981

---

💛 - Coveralls

[jakelishman]

Rebased over main and no longer on hold.