[contract-deploy] Macro for emitting an initialization nullifier in the constructor

[spalladino]

Contract constructors should now emit an "initialization nullifier", which signals that the contract has been constructed. This prevents a contract from being initialized more than once. The code for emitting the initialization nullifier should be injected under the hood by a macro.

Test that a contract cannot be initialized more than once, either when called from another contract (in the same or in different txs) or when called directly from aztecjs. Note that this allows fixing tests broken in #4056.

[spalladino]

Closing as done