[Feature] Ethereum-like interface for programs

[HarukaMa]

🚀 Feature

We should have something like interface to support calling for any program that adheres to a specified interface.

Motivation

We will inevitably have token standards (there are 2 ARC-20 proposals now), however under the current program framework, a program can only call hardcoded other programs. This would make token standards much less useful (except for wallet implementations), as one program will be only able to use one specified token. Having interface to enable calling any programs that adheres to ARC-20 standard could be crucial for applications.

Implementation

I guess this is the most complicated part, especially considering ZK constructs involved in the process.

Are you willing to open a pull request? (See CONTRIBUTING)
Out of my reach, unfortunately.