Add tools for doing accurate resource estimation on circuits

[tanujkhattar]

We have recently added a bunch of primitives for simulating chemistry Hamiltonian's. However, the ultimate goal is to be able to do resource estimation on circuits constructed using these primitives. Write an analogue of QCTraceSimulator in Q# that can consume Cirq circuits and do resource estimation on those circuits.

Some Potential design considerations for accurate resource estimation by compiling the constructed circuits:

• cirq.estimate_resources(circuit, config = esimation_config, gateset = target_gateset) where target_gateset can be T + Cliffords + Measurement, Toffoli + Cliffords + Measurement etc.
• Implement (hardcoded + analytical) decompositions of known (and unknown) gates into the target gatesets supported above by resource estimation.
• Provide support for different resource estimation configurations (for example: control tradeoff between optimizing for depth vs qubit count).
• Find a way of replacing different implementations of a primitive (eg: AND / Swap / etc.) that have different decompositions optimized for T-count / circuit depth / qubit count etc.

[mpharrigan]

I'd like to try just shoving in a sympy.Symbol for some of the GateWithRegisters' bitsize arguments and see what the t-count protocol makes of it. We could already have a symbolic/asymptotic protocol without knowing it!

[mpharrigan]

closing in favor of #539 #735 and other more-specific issues