replace 0x${string} by viem address

[eduramme]

I can replace this by the viem's Address type, but I didn't add this MessageData type in this task, I only moved all types from blockchain-txs.ts to a new file to keep the types in a separated file. Maybe we should make a task to replace 0x${string} to "Address" and "Hex" in the whole codebase.

@lgahdl