ProcessManager: Add a "Memory map" view to show a process's VM layout.

Fetch all the data from /proc/PID/vm for the selected process and show it
in a nice GTableView. :^)

Applications/ProcessManager/ProcessMemoryMapModel.h

@@ -0,0 +1,32 @@
+#pragma once
+
+#include <AK/JsonArray.h>
+#include <LibGUI/GModel.h>
+
+class ProcessMemoryMapModel final : public GModel {
+public:
+    enum Column {
+        Address,
+        Size,
+        AmountResident,
+        Access,
+        Name,
+        __Count
+    };
+
+    ProcessMemoryMapModel() {}
+    virtual ~ProcessMemoryMapModel() override {}
+
+    virtual int row_count(const GModelIndex& = GModelIndex()) const override;
+    virtual int column_count(const GModelIndex& = GModelIndex()) const override { return Column::__Count; }
+    virtual String column_name(int) const override;
+    virtual ColumnMetadata column_metadata(int) const override;
+    virtual GVariant data(const GModelIndex&, Role = Role::Display) const override;
+    virtual void update() override;
+
+    void set_pid(pid_t);
+
+private:
+    JsonArray m_process_vm;
+    int m_pid { -1 };
+};