Adding data access functions
Adding data access functions

TransactionProposal.GetBytes, deprecates ChainExtension.GetProposalBytes
and TransactionProposalResponse.GetPayload

Change-Id: Iffebe7328ca7388b58ab2758a8f592c643b5a96b
Signed-off-by: Karl Einholz <79221a1f750628e5863a1f872b200f185f72b9f5@securekey.com>

x2cn/artchain,warm3snow/fabric-sdk-go,artchainHangzhou/artchain2,warm3snow/fabric-sdk-go,x2cn/artchain,warm3snow/fabric-sdk-go,artchainHangzhou/artchain2,artchainHangzhou/artchain2,x2cn/artchain,x2cn/artchain,artchainHangzhou/artchain2