AK: Find a value in any container offering iterators

Problem:
- `find` is implemented inside of each container. This coupling
  requires that each container needs to individually provide `find`.

Solution:
- Decouple the `find` functionality from the container. This allows
  provides a `find` algorithm which can work with all
  containers. Containers can still provide their own `find` in the
  case where it can be optimized.
- This also allows for searching sub-ranges of a container rather than
  the entire container as some of the container-specific member
  functions enforced.

Note:
- @davidstone's talk from 2015 C++Now conference entitled "Functions
  Want to be Free" encourages this style:
  (https://www.youtube.com/watch?v=_lVlC0xzXDc), but it does come at
  the cost of composability.
- A logical follow-on to this is to provide a mechanism to use a
  short-hand function which automatically searches the entire
  container. This could automatically use the container-provided
  version if available so that functions which provide their own
  optimized version get the benefit.

AK/Traits.h

@@ -35,7 +35,7 @@ template<typename T>
 struct GenericTraits {
     using PeekType = T;
     static constexpr bool is_trivial() { return false; }
-    static bool equals(const T& a, const T& b) { return a == b; }
+    static constexpr bool equals(const T& a, const T& b) { return a == b; }
 };
 
 template<typename T>