NumPy Style indexing for `IList`.

[weinbe58]

Because we do not support list comprehension certain kinds of operations that invole non-uniform slicing of an IList can be very verbose. It would be nice if we could index an IList with an integer IList:

@structural
def main():
    a = ilist.range(100)
    return [a[0], a[1], a[4], a[7], a[10], a[55]]

could be written as:

@structural
def main():
    a = ilist.range(100)
    return a[[0, 1, 4, 7, 10, 55]]

[johnzl-777]

+1, would be incredibly helpful for QEC-related kernels