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/Time/APICTimer.cpp

@@ -16,7 +16,7 @@ namespace Kernel {
 
 UNMAP_AFTER_INIT APICTimer* APICTimer::initialize(u8 interrupt_number, HardwareTimerBase& calibration_source)
 {
-    auto timer = adopt_ref(*new APICTimer(interrupt_number, nullptr));
+    auto timer = adopt_lock_ref(*new APICTimer(interrupt_number, nullptr));
     timer->register_interrupt_handler();
     if (!timer->calibrate(calibration_source)) {
         return nullptr;