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/AnonymousFile.cpp

@@ -10,7 +10,7 @@
 
 namespace Kernel {
 
-AnonymousFile::AnonymousFile(NonnullRefPtr<Memory::AnonymousVMObject> vmobject)
+AnonymousFile::AnonymousFile(NonnullLockRefPtr<Memory::AnonymousVMObject> vmobject)
     : m_vmobject(move(vmobject))
 {
 }