Start adding a basic /proc filesystem and a "ps" utility.

Kernel/ProcFileSystem.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <AK/Types.h>
+#include <VirtualFileSystem/SyntheticFileSystem.h>
+
+class ProcFileSystem final : public SyntheticFileSystem {
+public:
+    virtual ~ProcFileSystem() override;
+    static RetainPtr<ProcFileSystem> create();
+
+    virtual bool initialize() override;
+    virtual const char* className() const override;
+
+private:
+    ProcFileSystem();
+};
+