refactor Renderer to make it more flexible

This is in preparation to supporting screen-space effects.
There are two major changes:

- RenderPass is now copiable and intended to be passed by copy to
  the execute stage of frame graph passes

- The color pass is in its own function now


This actually simplify RenderPass api.

libs/utils/include/utils/Slice.h

@@ -163,6 +163,8 @@ public:
     using size_type         = typename Slice<T, SIZE_TYPE>::size_type;
 
     GrowingSlice() noexcept = default;
+    GrowingSlice(GrowingSlice const& rhs) noexcept = default;
+    GrowingSlice(GrowingSlice&& rhs) noexcept = default;
 
     template<typename Iter>
     GrowingSlice(Iter begin, size_type count) noexcept
@@ -180,7 +182,7 @@ public:
     template<typename Iter>
     void set(Iter begin, size_type count) UTILS_RESTRICT noexcept {
         this->Slice<T, SIZE_TYPE>::set(begin, count);
-       mCapOffset = count;
+        mCapOffset = count;
     }
 
     template<typename Iter>