Begin work separating selection code from rectangle select tool

src/DrawingProgram/DrawingProgramSelection.hpp

@@ -0,0 +1,23 @@
+#pragma once
+#include "DrawingProgramCache.hpp"
+
+class DrawingProgram;
+
+class DrawingProgramSelection {
+    public:
+        DrawingProgramSelection(DrawingProgram& initDrawP);
+        void add_from_cam_coord_collider_to_selection(const SCollision::ColliderCollection<float>& cC);
+        void deselect_all();
+        void update();
+        void draw(SkCanvas* canvas, const DrawData& drawData);
+        bool is_something_selected();
+    private:
+        void calculate_aabb();
+        bool mouse_collided_with_selection_aabb();
+
+        SCollision::AABB<WorldScalar> selectionAABB;
+        CoordSpaceHelper selectionTransformCoords;
+        std::unordered_set<CollabListType::ObjectInfoPtr> selectedSet;
+        DrawingProgramCache cache;
+        DrawingProgram& drawP;
+};