feat: detect contract start

[bonustrack]

We should have a way to detect when a contract started, this would simplify setup and reduce mistakes (not having to set a custom start).

[TobieTom]

Hola I'm Tobias. I would like to take over this issue. I've already contributed to some projects recently since I just learned Rust and Cairo. I also have experience with js and typescript from web app projects in uni

[bonustrack]

This is not really needed and / or a priority.