Kernel: Rename Range => VirtualRange

...and also RangeAllocator => VirtualRangeAllocator.

This clarifies that the ranges we're dealing with are *virtual* memory
ranges and not anything else.

Kernel/Memory/VirtualRange.h

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, Leon Albrecht <leon2002.la@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <Kernel/KResult.h>
+#include <Kernel/VirtualAddress.h>
+
+namespace Kernel::Memory {
+
+class VirtualRange {
+    friend class VirtualRangeAllocator;
+
+public:
+    VirtualRange() = delete;
+    VirtualRange(VirtualAddress base, size_t size)
+        : m_base(base)
+        , m_size(size)
+    {
+    }
+
+    VirtualAddress base() const { return m_base; }
+    size_t size() const { return m_size; }
+    bool is_valid() const { return !m_base.is_null(); }
+
+    bool contains(VirtualAddress vaddr) const { return vaddr >= base() && vaddr < end(); }
+
+    VirtualAddress end() const { return m_base.offset(m_size); }
+
+    bool operator==(VirtualRange const& other) const
+    {
+        return m_base == other.m_base && m_size == other.m_size;
+    }
+
+    bool contains(VirtualAddress base, size_t size) const
+    {
+        if (base.offset(size) < base)
+            return false;
+        return base >= m_base && base.offset(size) <= end();
+    }
+
+    bool contains(VirtualRange const& other) const
+    {
+        return contains(other.base(), other.size());
+    }
+
+    Vector<VirtualRange, 2> carve(VirtualRange const&) const;
+    VirtualRange intersect(VirtualRange const&) const;
+
+    static KResultOr<VirtualRange> expand_to_page_boundaries(FlatPtr address, size_t size);
+
+private:
+    VirtualAddress m_base;
+    size_t m_size { 0 };
+};
+
+}
+
+template<>
+struct AK::Formatter<Kernel::Memory::VirtualRange> : Formatter<FormatString> {
+    void format(FormatBuilder& builder, Kernel::Memory::VirtualRange value)
+    {
+        return Formatter<FormatString>::format(builder, "{} - {} (size {:p})", value.base().as_ptr(), value.base().offset(value.size() - 1).as_ptr(), value.size());
+    }
+};