feat: add Create/Remove Task request (#150)

* feat: add Create/Remove Task request

* chore: all supported impls

* feat: flow.server.proto

* feat: add affected task ids

* chore: make all

* chore: typo

* refactor: use u32 for `TaskId`

proto/greptime/v1/ddl.proto

@@ -33,9 +33,30 @@ message DdlRequest {
     AlterExpr alter = 3;
     DropTableExpr drop_table = 4;
     TruncateTableExpr truncate_table = 7;
+    CreateTaskExpr create_task = 8;
+    RemoveTaskExpr remove_task = 9;
   }
 }
 
+// Create a flow task to run the SQL when new data arrives.
+message CreateTaskExpr {
+  string catalog_name = 1;
+  string task_name = 2;
+  string output_schema_name = 3;
+  string output_table_name = 4;
+  bool create_if_not_exists = 5;
+  string expire_when = 6;
+  string comment = 7;
+  string sql = 8;
+  map<string, string> task_options = 9;
+}
+
+// Remove a flow task.
+message RemoveTaskExpr {
+  string catalog_name = 1;
+  string task_name = 2;
+}
+
 message CreateTableExpr {
   string catalog_name = 1;
   string schema_name = 2;