Merge transaction circuits into one

[moCello]

Summary

Currently the circuits that need to be proven to create a transaction in zk are split into multiple parts: the execute circuits, send to contract and withdraw from contract. To simplify transactions, possibly reduce the gate counts and speed up proof creation, we want to merge the transfer circuit into a singular circuit based on the diagram in the protocol specifications.

Possible Solution

With this effort we also want to add the circuit directly in phoenix-core, as it is part of the phoenix protocol.