refactor: migrate ProcessMessage definitions to MessageProcessingResult, drop PeerMsgRet - #6820

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Process completed with exit code 1.

Potential conflicts detected!

{ pull_number: 6820, conflictPrs: [ { number: 6468, files: [ 'src/net_processing.cpp' ], conflicts: [ 'src/net_processing.cpp' ] }, { number: 6611, files: [ 'src/chain.h', 'src/consensus/params.h', 'src/net_processing.cpp', 'src/node/miner.cpp', 'src/primitives/block.h', 'src/timedata.cpp', 'src/timedata.h', 'src/validation.cpp' ], conflicts: [ 'src/net_processing.cpp' ] }, { number: 6595, files: [ 'src/init.cpp', 'src/net_processing.cpp', 'src/qt/test/wallettests.cpp', 'src/rest.cpp', 'src/test/interfaces_tests.cpp', 'src/test/validation_block_tests.cpp', 'src/test/validation_chainstatemanager_tests.cpp', 'src/txorphanage.cpp', 'src/txorphanage.h', 'src/validation.h', 'src/wallet/rpcwallet.cpp', 'src/wallet/test/spend_tests.cpp', 'src/wallet/test/wallet_tests.cpp' ], conflicts: [ 'src/net_processing.cpp' ] }, { number: 6683, files: [ 'src/Makefile.bench.include', 'src/bench/streams_findbyte.cpp', 'src/net.cpp', 'src/net.h', 'src/net_processing.cpp', 'src/streams.h', 'src/test/fuzz/buffered_file.cpp', 'src/test/streams_tests.cpp', 'src/validation.cpp', 'src/wallet/rpcdump.cpp', 'test/functional/wallet_importmulti.py' ], conflicts: [ 'src/net_processing.cpp' ] }, { number: 6714, files: [ 'src/bench/coin_selection.cpp', 'src/bench/wallet_balance.cpp', 'src/bitcoin-wallet.cpp', 'src/bitcoind.cpp', 'src/chain.cpp', 'src/dummywallet.cpp', 'src/index/base.cpp', 'src/index/blockfilterindex.cpp', 'src/index/coinstatsindex.cpp', 'src/index/coinstatsindex.h', 'src/index/txindex.cpp', 'src/init.cpp', 'src/init.h', 'src/init/bitcoin-node.cpp', 'src/init/bitcoind.cpp', 'src/interfaces/chain.h', 'src/interfaces/init.h', 'src/interfaces/node.h', 'src/interfaces/wallet.h', 'src/net_processing.cpp', 'src/node/blockstorage.cpp', 'src/node/blockstorage.h', 'src/node/caches.cpp', 'src/node/caches.h', 'src/node/chainstate.cpp', 'src/node/chainstate.h', 'src/node/coin.cpp', 'src/node/coin.h', 'src/node/coinstats.cpp', 'src/node/coinstats.h', 'src/node/context.cpp', 'src/node/context.h', 'src/node/interfaces.cpp', 'src/node/miner.cpp', 'src/node/miner.h', 'src/node/minisketchwrapper.cpp', 'src/node/minisketchwrapper.h', 'src/node/psbt.cpp', 'src/node/psbt.h', 'src/node/transaction.cpp', 'src/node/transaction.h', 'src/node/utxo_snapshot.h', 'src/qt/bitcoin.cpp', 'src/qt/coincontroldialog.cpp', 'src/qt/coincontroldialog.h', 'src/qt/psbtoperationsdialog.cpp', 'src/qt/sendcoinsdialog.cpp', 'src/qt/sendcoinsdialog.h', 'src/qt/test/addressbooktests.cpp', 'src/qt/test/test_main.cpp', 'src/qt/test/wallettests.cpp', 'src/qt/transactiondesc.cpp', 'src/qt/transactionrecord.cpp', 'src/qt/walletcontroller.cpp', 'src/qt/walletmodel.cpp', 'src/qt/walletmodel.h', 'src/rest.cpp', 'src/rpc/blockchain.cpp', 'src/rpc/blockchain.h', 'src/rpc/mining.cpp', 'src/rpc/misc.cpp', 'src/rpc/net.cpp', 'src/rpc/rawtransaction.cpp', 'src/rpc/server_util.cpp', 'src/rpc/server_util.h', 'src/test/blockfilter_index_tests.cpp', 'src/test/coinstatsindex_tests.cpp', 'src/test/fuzz/coins_view.cpp', 'src/test/fuzz/deserialize.cpp', 'src/test/fuzz/minisketch.cpp', 'src/test/fuzz/psbt.cpp', 'src/test/fuzz/tx_pool.cpp', 'sr