Kernel: Make self-contained locking smart pointers their own classes

Until now, our kernel has reimplemented a number of AK classes to
provide automatic internal locking:

- RefPtr
- NonnullRefPtr
- WeakPtr
- Weakable

This patch renames the Kernel classes so that they can coexist with
the original AK classes:

- RefPtr => LockRefPtr
- NonnullRefPtr => NonnullLockRefPtr
- WeakPtr => LockWeakPtr
- Weakable => LockWeakable

The goal here is to eventually get rid of the Lock* classes in favor of
using external locking.

Kernel/Bus/USB/USBPipe.h

@@ -67,7 +67,7 @@ public:
 private:
     friend class Device;
 
-    NonnullRefPtr<USBController> m_controller;
+    NonnullLockRefPtr<USBController> m_controller;
 
     Type m_type;
     Direction m_direction;