Revert "Merge branch 'discord'"

This reverts commit e7b9a57723, reversing
changes made to 02b4aa3c91.

Revert "moved rapidjson files"

This reverts commit f5012f770c.

include/misc/DiscordRPC.h

@@ -1,15 +0,0 @@
-#pragma once
-
-#include <string>
-
-namespace td {
-namespace utils {
-
-void InitDiscordRPC();
-void UpdateDiscordRPC();
-void ShutdownDiscordRPC();
-
-void UpdateDiscordPresence(const std::string& state, const std::string& details, bool resetTimer = false);
-
-} // namespace utils
-} // namespace td