Burner remove options

[Matth26]

• Introduced a BurnerProvider within create-burner to allow the passing of initialization variables to useBurner without having to provide them as props.
• Replaced rpcUrl with rpcProvider and initialized it within the DojoContext. In the past, it was created inside the useBurner constructor. This could lead to confusion since rpc_url was optional and defaulted to http://localhost:5050/ in the burner.

[Matth26]

Issue #41 has been fixed when extracting the RpcProvider instantiation from the create-burner package

Issue #38 fixed: add "Save Burners to Clipboard" and a "Restore Burners from Clipboard" buttons in react-app example and add save and restore functions in create-burner package

[ponderingdemocritus]

Looks great!