Support execute callback by label or address

[assafmo]

Currently can only call by address: https://github.com/enigmampc/SecretNetwork/blob/b62073aa72f2cfc9101927cb6e6c7a2836bb734c/cosmwasm/packages/std/src/init_handle.rs#L92-L100

[Cashmaney]

@assafmo same as #574 ?

[assafmo]

Yes, closing #574