Discord rich presence (#4500)

* WIP RPC support

* Might have windows support now, don't peek

* Windows support

* RichPresence: __SWITCH__ => DISABLE_RPC (for MOBILE_STK support)

* RichPresence: Handle JSON strings according to spec, support for addons icon

* RichPresence: use translated difficulty name

* RichPresence: disable when client_id=-1

* RichPresence: thread connection, show server name on RPC

* RichPresence: destroy on close

* RichPresence: don't compile methods at all if DISABLE_RPC

* RichPresence: fix windows compile (untested)

* RichPresence: fix for mac

* RichPresence: Linux needs MSG_NOSIGNAL still

* RichPresence: fix memory leaks, don't spam update while not connected

* RichPresence: free thread on terminate

* RichPresence: handle initial registration

* RichPresence: fix compiler warning

src/main_loop.cpp

@@ -56,6 +56,7 @@
 #include "utils/string_utils.hpp"
 #include "utils/time.hpp"
 #include "utils/translation.hpp"
+#include "io/rich_presence.hpp"
 
 #ifndef WIN32
 #include <unistd.h>
@@ -714,6 +715,8 @@ void MainLoop::run()
                 }
             }
 
+            RichPresenceNS::RichPresence::get()->update(false);
+
             if (auto gp = GameProtocol::lock())
             {
                 gp->sendActions();