Cairo 2.9.1 and improve api

[edg-l]

• Updates to cairo 2.9.1
• Removes an unnecesary Cell
• Adds Clone and Debug to VM struct
• Changes VM struct so it doesnt hold a syscall handler, instead its passed to the .step(), removing generics and allowing the end user to hold the VM struct in a more usable way (specially in the sequencer this allows to create the VM and then run it later, like cairo native)
• Change call_contract to accept a selector instead of function id, like cairo native does.
• Removes the gitignore on Cargo.lock for easier reproducing
• Adds run_with_trace to simplify more.
• Adds LICENSE with Apache 2.0
• Improves the readme

[FrancoGiachetta]

LGTM!