Kernel/Locking: Add lock rank tracking per thread to find deadlocks

This change adds a static lock hierarchy / ranking to the Kernel with
the goal of reducing / finding deadlocks when running with SMP enabled.

We have seen quite a few lock ordering deadlocks (locks taken in a
different order, on two different code paths). As we properly annotate
locks in the system, then these facilities will find these locking
protocol violations automatically

The `LockRank` enum documents the various locks in the system and their
rank. The implementation guarantees that a thread holding one or more
locks of a lower rank cannot acquire an additional lock with rank that
is greater or equal to any of the currently held locks.

Kernel/Locking/LockRank.cpp

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2021, Brian Gianforcaro <bgianf@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <Kernel/Locking/LockRank.h>
+#include <Kernel/Thread.h>
+
+// Note: These stubs can't be in LockRank.h as that would create
+// a cyclic dependency in the header include graph of the Kernel.
+
+namespace Kernel {
+
+void track_lock_acquire(LockRank rank)
+{
+    auto thread = Thread::current();
+    if (thread && !thread->is_crashing())
+        thread->track_lock_acquire(rank);
+}
+
+void track_lock_release(LockRank rank)
+{
+    auto thread = Thread::current();
+    if (thread && !thread->is_crashing())
+        thread->track_lock_release(rank);
+}
+
+}