Exp/compress candidates (#942)

* Compress block candidates in validator-session

* Compress blocks in full-node (disabled for now)

---------

Co-authored-by: SpyCheese <mikle98@yandex.ru>

validator-session/candidate-serializer.h

@@ -0,0 +1,29 @@
+/*
+    This file is part of TON Blockchain Library.
+
+    TON Blockchain Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    TON Blockchain Library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with TON Blockchain Library.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#pragma once
+#include "ton/ton-types.h"
+#include "auto/tl/ton_api.h"
+
+namespace ton::validatorsession {
+
+td::Result<td::BufferSlice> serialize_candidate(const tl_object_ptr<ton_api::validatorSession_candidate> &block,
+                                                bool compression_enabled);
+td::Result<tl_object_ptr<ton_api::validatorSession_candidate>> deserialize_candidate(td::Slice data,
+                                                                                     bool compression_enabled,
+                                                                                     int max_decompressed_data_size);
+
+}  // namespace ton::validatorsession