Optimize reduced opening calculation in static verifier

[jonathanpwang]

In the halo2 static verifier, currently profiling shows that the reduced opening calculation (which is linear in number of columns) is a significant contributor to the cells of the halo2 circuit. See here for explanation of reduced opening. Todo: add link to profiling.

Investigate reducing the cell count either by more efficient use of halo2-base via better instructions in eDSL or by making a custom gate for reduced opening similar to what is doing in the Aggregation VM.