AK: Reimplement all_of in terms of find_if

Problem:
- Now that a generic free-function form of `find_if` is implemented
  the code in `all_of` is redundant.

Solution:
- Follow the "don't repeat yourself" mantra and make the code DRY by
  implementing `all_of` in terms of `find_if`.
- One tricky part is that since captures are not permitted in
  `constexpr` lambdas, the lambda created to negate the predicate
  needs to be created by a function which does not capture and takes
  the predicate at run-time instead. This allows `all_of` to continue
  to work in a `constexpr` context.

AK/AllOf.h

@@ -7,6 +7,7 @@
 #pragma once
 
 #include <AK/Concepts.h>
+#include <AK/Find.h>
 #include <AK/Iterator.h>
 
 namespace AK {
@@ -17,22 +18,16 @@ constexpr bool all_of(
     TEndIterator const& end,
     auto const& predicate)
 {
-    for (auto iter = begin; iter != end; ++iter) {
+    constexpr auto negated_predicate = [](auto const& pred) {
-        if (!predicate(*iter)) {
+        return [&](auto const& elem) { return !pred(elem); };
-            return false;
+    };
-        }
+    return !(find_if(begin, end, negated_predicate(predicate)) != end);
-    }
-    return true;
 }
 
 template<IterableContainer Container>
 constexpr bool all_of(Container&& container, auto const& predicate)
 {
-    for (auto&& entry : container) {
+    return all_of(container.begin(), container.end(), predicate);
-        if (!predicate(entry))
-            return false;
-    }
-    return true;
 }
 
 }