Seed the KdTree nearest-neighbour distance with the squared-distance type's max

Summary:
`nearestNeighbor()` writes its result into a `SquareValueTyper<T>::Type`, but seeded the
sentinel from `T`. For floating point the two types are identical, so nothing was wrong
there. For every integer instantiation they differ and the sentinel is far too small -
`SquareValueTyper<short>::Type` is `unsigned int` (max 4294967295) while
`numeric_limits<short>::max()` is 32767.

The recursive helper only assigns `nearest` inside `if (localDistance < distance)`, so any
tree whose closest point sits farther than that sentinel returned no candidate at all. For
`short` that is any coordinate delta beyond about 181.

___

Differential Revision: D114541610

fbshipit-source-id: 4745518e0e6fce1e18ccb6808ff9250b04973ed8

Author: janherlingmeta

impl/ocean/base/KdTree.h

@@ -340,7 +340,7 @@ const T* KdTree<T>::nearestNeighbor(const T* value, typename SquareValueTyper<T>
 {
 	ocean_assert(value);
 
-	distance = std::numeric_limits<T>::max();
+	distance = std::numeric_limits<typename SquareValueTyper<T>::Type>::max();
 
 	if (!root_)
 	{