Tezt: add bootstrap contracts to setup

What

This MR adds bootstrap smart contracts to tezlink, by providing test helper functions and writing the information on the durable storage via kernel configuration.

How

• Add tez_bootstrap_contracts to tezt setup, using a record containing the address to deploy the contract, a path to the contract, and the initial storage;
• Add tez-bootstrap_contract to kernel config, receiving a string of comma-separated values corresponding to the contract address, the hexadecimal representation of the code, and the hexadecimal representation of the initial storage;
• Add the get_storage RPC
• Add a test to fetch the storage of a bootstrap contract;

Manually testing the MR

dune exec etherlink/tezt/tests/main.exe -- /threshold_encryption /dal alpha tezlink storage