Implement Self-Upgradable Smart Contract with self_upgrade function (DAO-Controlled)

[sczembor]

Self-upgradable smart contract tutorial. The contract would include a self_upgrade function that allows a designated address (typically a DAO) to initiate an upgrade process.

Functionality:

• The self_upgrade function would accept new WASM code as input.
• Upon receiving a valid call from the authorized address, the contract would update its internal logic with the provided WASM code.