general: Get the current process program id directly from the system

This allows us to avoid including KProcess' header file in files that only need to get the current process' program id.

src/core/core.cpp

@@ -639,6 +639,10 @@ const Core::SpeedLimiter& System::SpeedLimiter() const {
     return impl->speed_limiter;
 }
 
+u64 System::GetCurrentProcessProgramID() const {
+    return impl->kernel.CurrentProcess()->GetProgramID();
+}
+
 Loader::ResultStatus System::GetGameName(std::string& out) const {
     return impl->GetGameName(out);
 }