Permissions on methods of contracts

[izyak]

We have methods on contract like createClient, which can be initialized with wrong data by some external party. It makes sense to impose some restriction on this method.

Similarly, on the ICON side, since the handshaking for channel and connection can emit BTP Blocks w/o much cost, we need to think of a way to prevent that. For this, we can either have permissioned methods, or we need to charge a certain amount of fee from the caller, so unnecessary BTP Blocks would not be generated.

[ibrizsabin]

I think in case of iarchway host we can make create client and upgrade client to be permissioned and other methods can be left open ao that any relayer can connect and send messages.