ABCI++: Update new protos to use enum instead of bool (#8158)

closes: #8039

This pull request updates the new ABCI++ protos to use `enum`s in place of `bool`s. `enums` may be preferred over `bool` because an `enum` can be udpated to include new statuses in the future, whereas a `bool` cannot and is fixed as just `true` or `false` over the whole lifecycle of the API.

state/execution.go

@@ -132,7 +132,7 @@ func (blockExec *BlockExecutor) CreateProposalBlock(
 		// Either way, we cannot recover in a meaningful way, unless we skip proposing
 		// this block, repair what caused the error and try again. Hence, we return an
 		// error for now (the production code calling this function is expected to panic).
-		return nil, err
+		panic(err)
 	}
 	txrSet := types.NewTxRecordSet(rpp.TxRecords)