API discussion on auto emulation rewrite step

[msoeken]

The auto emulation feature (microsoft/qsharp-runtime#514) requires a new public attribute, currently called

@EmulateWith("Alternative", "Simulator")
operation Op() : ...

to express that Op should be executed as Alternative when run in Simulator.

This issue should enable discussions on the API for this PR.

[cgranade]

Thanks for opening this, @msoeken! It looks from microsoft/qsharp-runtime#514 like the new attribute would be in the Microsoft.Quantum.Core namespace, is that correct?

[msoeken]

Yes, that is correct.

[cgranade]

As per #426, this has been approved modulo the changes discussed in that review. Thanks for driving this!