Refactor transfer contract

[moCello]

Summary

Refactor the transfer-contract.

Detailed Description

This refactor will include:

• merge transfer-types and stake-types into a single library that also re-exports phoenix-core types and functionality as well as other keys and signature types Add execution-core library #1780
• remove the transfer-circuits as they moved to phoenix-circuits and integrate to phoenix-core v0.28 Remove transfer-circuits, update to phoenix 2.0 #1809 and Remove circuit caching mechanism from the circuits-dir #1810
• refactor the transfer contract after those changes

Relevant Context

phoenix #175
phoenix #169

[HDauven]

Closing, resolved by #1822