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/FileSystem/SysFS/Subsystems/Bus/Directory.cpp

@@ -10,9 +10,9 @@
 
 namespace Kernel {
 
-UNMAP_AFTER_INIT NonnullRefPtr<SysFSBusDirectory> SysFSBusDirectory::must_create(SysFSRootDirectory const& parent_directory)
+UNMAP_AFTER_INIT NonnullLockRefPtr<SysFSBusDirectory> SysFSBusDirectory::must_create(SysFSRootDirectory const& parent_directory)
 {
-    auto directory = adopt_ref(*new (nothrow) SysFSBusDirectory(parent_directory));
+    auto directory = adopt_lock_ref(*new (nothrow) SysFSBusDirectory(parent_directory));
     return directory;
 }