Kernel: Add PerformanceManager static class, move perf event APIs there

The current method of emitting performance events requires a bit of
boiler plate at every invocation, as well as having to ignore the
return code which isn't used outside of the perf event syscall. This
change attempts to clean that up by exposing high level API's that
can be used around the code base.

Kernel/Process.h

@@ -492,6 +492,7 @@ private:
     friend class MemoryManager;
     friend class Scheduler;
     friend class Region;
+    friend class PerformanceManager;
 
     bool add_thread(Thread&);
     bool remove_thread(Thread&);