AK: Implement wrapper for reverse range for loop

Now it is possible to use range for loop in reverse mode for a
container.
```
	for (auto item : in_reverse(vector))
```

AK/ReverseIterator.h

@@ -87,4 +87,22 @@ class SimpleReverseIterator {
  int m_index { 0 };
 };
 
+namespace ReverseWrapper {
+
+template<typename Container>
+struct ReverseWrapper {
+ Container& container;
+};
+
+template<typename Container>
+auto begin(ReverseWrapper<Container> wrapper) { return wrapper.container.rbegin(); }
+
+template<typename Container>
+auto end(ReverseWrapper<Container> wrapper) { return wrapper.container.rend(); }
+
+template<typename Container>
+ReverseWrapper<Container> in_reverse(Container&& container) { return { container }; }
+
+}
+
 }

Tests/AK/TestVector.cpp

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include "AK/ReverseIterator.h"
 #include <LibTest/TestCase.h>
 
 #include <AK/NonnullOwnPtrVector.h>
@@ -552,10 +553,18 @@ TEST_CASE(rend)
  EXPECT_EQ(*expected, *expected_in_reverse);
 }
 
-TEST_CASE(reverse_loop)
+TEST_CASE(reverse_iterator_for_loop)
 {
  Vector<int> v { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
  int index = 9;
  for (auto rev = v.rbegin(); rev != v.rend(); ++rev)
  EXPECT_EQ(*rev, index--);
 }
+
+TEST_CASE(reverse_range_for_loop)
+{
+ Vector<int> v { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
+ int index = 9;
+ for (auto item : AK::ReverseWrapper::in_reverse(v))
+ EXPECT_EQ(item, index--);
+}