Fix kernel builder c_if qubit extraction bug

[anthony-santana]

Description

• Fixes an issue where qubits that are extracted in a then function were not getting a unique extract_ref if used outside of the conditional
• Adds new python and C++ tests to test for this bug

    kernel = cudaq.make_kernel()
    qubits = kernel.qalloc(2)

    kernel.x(qubits[0])
    measure = kernel.mz(qubits[0], "measure0")

    def then():
        kernel.x(qubits[1])

    kernel.c_if(measure, then)

    # With bug, any use of `qubits[1]` again would throw a
    # runtime error.
    kernel.x(qubits[1])
    kernel.x(qubits[1])

    result = cudaq.sample(kernel)

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[anthony-santana]

/ok to test

Command Bot: Processing...

[github-actions]

CUDA Quantum Docs Bot: A preview of the documentation can be found here.

[amccaskey]

Looking at this, I'm pretty sure the code you've removed was put there before we had the canonicalizers that combined like extracts. Good to see the old stuff get cleaned up.

[anthony-santana]

/ok to test

Command Bot: Processing...

[schweitzpgi]

+1