Function find_contract_id 

fn find_contract_id<'gcx>(
    gcx: Gcx<'gcx>,
    name: &str,
    abs_sol_path: &Path,
) -> Option<ContractId>

Find the HIR ContractId for a contract by name, requiring the contract to live in the source file currently being rendered (compared via absolute path) so contracts that share a file stem across src/ and lib/ cannot collide.