shard: support for sharing rocksdb and init LogsDB CFs

cpp/core/LogsDB.cpp

@@ -0,0 +1,9 @@
+#include "LogsDB.hpp"
+
+std::vector<rocksdb::ColumnFamilyDescriptor> LogsDB::getColumnFamilyDescriptors() {
+    return {
+        {"logMetadata",{}},
+        {"logTimePartition0",{}},
+        {"logTimePartition1",{}},
+    };
+}