Handle error when adding a frontier chain with no deploy-config

[geoknee]

We should modify this code:

superchain-registry/add-chain/main.go

Lines 196 to 201 in acb5f92

	err = copyDeployConfigFile(deployConfigPath, genesisValidationInputsDir)
	if err != nil {
	return fmt.Errorf("error copying deploy-config json file: %w", err)
	}
	fmt.Printf("✅ Copied deploy-config json file to validation module\n")

so that if the chain is frontier and not a standard candidate, we swallow the error and print out a meaningful message since we do not require this information for chains that won't ever be subject to the genesis-allocs validation.