Allow get_state to return state vector and results from mid-circuit measurement

[mawolf2023]

Required prerequisites

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Describe the feature

For use cases like magic state distillation, a user needs to use a kernel that performs mid-circuit measurement on some of the qubits and allows extraction of the the resulting state vector and the mid-circuit measurement results.

@cudaq.kernel
def kernel():
    reg=cudaq.qvector(2)

    a = mz(reg[1])



state, measurements = cudaq.get_state(kernel)  # Returns SV and list of mid-circuit measurements. 
   

This is used for QEC applications where the measurements are syndromes and determine if the resulting state is good or not, so both results need to be extracted from a single kernel execution.

PS: It would also be helpful if the SV that is returned is the dimension of the Hilbert space of the unmeasured qubits. This would allow easy computation of the overlap between this result and a noiseless state.