Kernel: Add mechanism to identity map the lowest 2MB

Author: https://github.com/tomuta
Commit: 841364b609
Pull-request: https://github.com/SerenityOS/serenity/pull/2475
Reviewed-by: https://github.com/awesomekling
Reviewed-by: https://github.com/bugaevc

Kernel/VM/RangeAllocator.h

@@ -90,6 +90,11 @@ public:
 
     void dump() const;
 
+    bool contains(const Range& range) const
+    {
+        return m_total_range.contains(range);
+    }
+
 private:
     void carve_at_index(int, const Range&);