improved diagnostics message when swapping array elements

[filipw]

At the moment it is easy to supply out of bounds indices when using array Swapped(...).

For example:

let arr = [1, 2, 3];
let swapped = LocalSwapped(0, 4, arr);

produces, on a default simulator:

Unhandled exception: System.ArgumentOutOfRangeException: Specified argument was out of the range of valid values.

This PR adds an extra bounds check, similar to what is already done elsewhere to convert the error message to a more helpful

Unhandled exception: Microsoft.Quantum.Simulation.Core.ExecutionFailException: Second index is out of bounds

[msoeken]

Thanks for your contribution @filipw

[msoeken]

/azp run

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