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/RootDirectory.cpp

@@ -13,9 +13,9 @@
 
 namespace Kernel {
 
-NonnullRefPtr<SysFSRootDirectory> SysFSRootDirectory::create()
+NonnullLockRefPtr<SysFSRootDirectory> SysFSRootDirectory::create()
 {
-    return adopt_ref(*new (nothrow) SysFSRootDirectory);
+    return adopt_lock_ref(*new (nothrow) SysFSRootDirectory);
 }
 
 SysFSRootDirectory::SysFSRootDirectory()