feat: add cross-chain output (#56)

feat: add cross-chain output (#56)

* refactor: move ComputeOutputID() for SpendCommitment

* wip: init OutputType

* refactor: rename NewTxOutput to NewIntraChainTxOutput

* wip: typed intra-chain output

* feat: add CrossChainTxOutput

* fix: fix CrossChainOutputType

* doc: update todo

* init bc

* fix

* wip: bc NewIntraChainOutput

* fix: bc IntraChainOutput

* fix: fix tx.Output()

* move ComputeOutputID back

* fix types.NewIntraChainTxOutput & types.NewCrossChainTxOutput

* doc: update todo

* fix: add VMVersion, ControlProgram and AssetAmount for types.Output

* fix map.go

* fix txfeed

* fix peer.go

* fi

* rename

* fix TxOutput.readFrom()

* fix TxOutput.readFrom()

* use currentAssetVersion

* clean

* update todos

* add cross-chain in mapTx.go

* doc: update comments

* wip: check IntraChainOutput source in validation

* wip: checkValidDest() checks CrossChainOutput

* fix checkStandardTx

* fix: fix checkStandardTx

* fix: fix TxOutput.writeTo()

* fix hard-coded AssetVersion

* roll back assetVersion

* refactor: rename ComputeOutputID

* refactor: rename ComputeOutputID()

* fix blockchain/txbuilder/txbuilder_test.go

* fix: fix crosschainOut as Input

* doc: fix comments

* wip

* clean

* fix

* fix

* fix

* fix

* fix

* fix

* fix

* fix

* fix

* clean

* fix

* fix

* fix

* fix

* fix

* fix wip

* should fix

* figure out

* fix comment

* fix estimate gas

* fixing

* try merkle

* fix merkle test

* fix merkle comp

* fix TestTxOutToUtxos()

* fix TestReadFrom

* minor

* try fix the ci