Optimize confcall join process.

Telegram/SourceFiles/tde2e/tde2e_api.cpp

@@ -102,6 +102,10 @@ PublicKey Call::myKey() const {
 	return _myKey;
 }
 
+bool Call::hasLastBlock0() const {
+	return _lastBlock0.has_value();
+}
+
 void Call::refreshLastBlock0(std::optional<Block> block) {
 	_lastBlock0 = std::move(block);
 }

Telegram/SourceFiles/tde2e/tde2e_api.h

@@ -95,6 +95,7 @@ public:
 	[[nodiscard]] QByteArray emojiHash() const;
 	[[nodiscard]] rpl::producer<QByteArray> emojiHashValue() const;
 
+	[[nodiscard]] bool hasLastBlock0() const;
 	void refreshLastBlock0(std::optional<Block> block);
 	[[nodiscard]] Block makeJoinBlock();
 	[[nodiscard]] Block makeRemoveBlock(const base::flat_set<UserId> &ids);