Kernel: Require lock rank for Spinlock construction

All users which relied on the default constructor use a None lock rank
for now. This will make it easier to in the future remove LockRank and
actually annotate the ranks by searching for None.

Kernel/FileSystem/VirtualFileSystem.h

@@ -98,7 +98,7 @@ private:
     RefPtr<Inode> m_root_inode;
     RefPtr<Custody> m_root_custody;
 
-    SpinlockProtected<Vector<Mount, 16>> m_mounts;
+    SpinlockProtected<Vector<Mount, 16>> m_mounts { LockRank::None };
 };
 
 }