Move pathfinders to dedicated files

cpp/src/pathfinder/base.cpp

@@ -0,0 +1,22 @@
+#include <memory>
+#include <cassert>
+#include <queue>
+
+#include "pathfinder/base.hpp"
+
+#include "log.hpp"
+#include "math.hpp"
+
+namespace pathfinder {
+
+PathFinderBase::PathFinderBase(const Map* map) : m_Map(map) {}
+
+// LinearPathFinder also lives here, since it is too small to get it's
+// own implementation file
+Path LinearPathFinder::CalculatePath(WorldPos start, WorldPos end)
+{
+  auto path = Path{end};
+  return path;
+}
+
+} // pathfinder namespace