[SC] Implicit prerequisite of value transfer

The KLAY, ERC20, and ERC721 tokens are transferrable to the registered counterpart chain via a bridge. However, the sender of value transfer transaction must be aware some of status. For instance, considering the KLAY transfer, the counterpart bridge must hold enough balance than requested KLAY.

KLAY: The receiver bridge must have enough balance at the time of value transfer request. ERC20: No further design or change is required if burning & minting mechanism is applied ERC721: The token ID must not be owned at the time of value transfer. Redesigned via #1460

Ongoing at #1565

Exalate commented: Issue Created by: hyunsooda

closed #1565