* Adding L1MessageSender to Transaction
* Adding logic to omit L1MessageSender in encoding / decoding when nil and never use it in hash computation
Co-authored-by: ben-chain <ben@pseudonym.party>
* les: move the checkpoint oracle into its own package
It's first step of refactor LES package. LES package
basically can be divided into LES client and LES server.
However both sides will use checkpoint package for
status retrieval and verification. So this PR moves
checkpoint oracle into a separate package
* les: address comments
