Write an RX-based Rabi experiment as a test

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Write a test which does a Rabi experiment and a sine-curve fit on successive RX angles. Something like:

data = []
angles = linspace([0, 2pi], 25)
num_shots = 100
for angle in angles:
    p = RX(angle) 0
    histogram = qvm(p, shots=num_shots)
    data += histogram[1]/num_shots
fit, error = fit_sinusoid(angles, data)
assert error < some_threshold

Intention is to emulate a somewhat common experimental setup.