💚 Implement CI workflow for Smart Contracts on-chain tests

[ccamel]

Background

Recently, we've faced a scenario where just changing the version of a component (Rust, in this case) had the potential to disrupt our smart contract execution - cf. https://github.com/okp4/contracts/pull/292#issuecomment-1659714840. Such cases can lead to disastrous problems if not detected early.

Proposal

To ascertain the proper functioning of the Smart Contracts within the OKP4 blockchain, I propose the addition of a new CI workflow designed to detect and resolve such disruption early in the development process. This workflow could incorporate a variety of tests, including on-chain deployment tests, as well as certain smart contract calls to validate the correct interaction of the contracts amongst themselves and with the entire blockchain.