feat: mito wal proto (#75)

* feat: row-based insert

* feat: null value

* roback: null value

* feat: delete by row

* feat: add wal proto

* feat: generate code

* feat: rename mutation type to op type

* feat: Generate code

* feat: An entry per region

* feat: remove region id from WalEntry

* refactor: move mito/wal to wal

* feat: gen

* feat: remove mito

---------

Co-authored-by: jiachun <jiachun_fjc@163.com>

proto/greptime/v1/wal.proto

@@ -0,0 +1,45 @@
+// Copyright 2023 Greptime Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package greptime.v1;
+
+option go_package = "github.com/GreptimeTeam/greptime-proto/go/greptime/v1";
+
+import "greptime/v1/row.proto";
+
+// Type of operation to rows.
+enum OpType {
+  // Delete rows.
+  DELETE = 0;
+  // Put rows.
+  PUT = 1;
+}
+
+// Mutation contains updates to a set of rows.
+message Mutation {
+  // Type of this mutation.
+  OpType op_type = 1;
+  // Start WAL sequence of this mutation.
+  uint64 sequence = 2;
+  // Row updates to write to the WAL.
+  Rows rows = 3;
+}
+
+// A WAL entry contains a list of mutations for a region to write.
+message WalEntry {
+  // List of mutations for a region.
+  repeated Mutation mutations = 1;
+}