g/jak2: initial Discord RPC implementation (#2100)

Notable things:
- This assert is hit when trying to save the pc-settings file, NYI
https://github.com/open-goal/jak-project/blob/e630b506903d7f7028dff89702be7f586c2120e7/game/kernel/common/Symbol4.h#L14
so right now settings aren't persisted. But RPC defaults to on
- The existing functions can probably be made generic based off the game
version, but I didn't spend time refactoring them yet as they aren't
really ready to be used in jak 2 yet (we have no screenshots for the
levels for example)

game/main.cpp

@@ -15,8 +15,6 @@
 #include "common/util/unicode_util.h"
 #include "common/versions.h"
 
-#include "game/discord.h"
-
 #ifdef _WIN32
 extern "C" {
 __declspec(dllexport) unsigned long NvOptimusEnablement = 0x00000001;
@@ -24,9 +22,6 @@ __declspec(dllexport) int AmdPowerXpressRequestHighPerformance = 1;
 }
 #endif
 
-// Discord RPC
-extern int64_t gStartTime;
-
 /*!
  * Set up logging system to log to file.
  * @param verbose : should we print debug-level messages to stdout?
@@ -87,10 +82,6 @@ int main(int argc, char** argv) {
     return 1;
   }
 
-  // set up discord stuff
-  gStartTime = time(nullptr);
-  init_discord_rpc();
-
   if (disable_avx2) {
     // for debugging the non-avx2 code paths, there's a flag to manually disable.
     printf("Note: AVX2 code has been manually disabled.\n");