Implement PRODUCT decomposition

[christopherkang]

I have performed a quick implementation of the PRODUCT function using the implementation suggested in https://arxiv.org/pdf/2007.07391 (page 69).

This addresses issue #485.

Some notes:

• This achieves the desired complexity and relies upon the AND bloq. It is important to use the AND bloq because the AND.adjoint natively allows us to uncompute without additional Toffoli complexity (by using the strategies from Gidney)
• It also includes a brute force test checking all implementations with input sizes ranging from 1-3 bits.
• My code as of now is not fully commented + notated --- I would appreciate feedback on making it better!

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