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/Graphics/GraphicsManagement.cpp

@@ -126,7 +126,7 @@ static inline bool is_display_controller_pci_device(PCI::DeviceIdentifier const&
 UNMAP_AFTER_INIT bool GraphicsManagement::determine_and_initialize_graphics_device(PCI::DeviceIdentifier const& device_identifier)
 {
     VERIFY(is_vga_compatible_pci_device(device_identifier) || is_display_controller_pci_device(device_identifier));
-    RefPtr<GenericGraphicsAdapter> adapter;
+    LockRefPtr<GenericGraphicsAdapter> adapter;
 
     if (!adapter) {
         switch (device_identifier.hardware_id().vendor_id) {