Add block support to JIT and JIT wrapper

The major additional complication here is registers and the notion of cycles. This cycle-aware evaluation will require changes to the interface to support setting inputs at particular cycles, and getting outputs similarly.

Start by locating the JIT and JIT wrapper interfaces and understanding how registers and cycles are represented. Define the required behavior for setting inputs at particular cycles and retrieving outputs at corresponding cycles; the work is done when block evaluation supports this cycle-aware interface.

Written by the indexing model from the issue text.