ENH: speed up timelapse pos pick

1. Cache the bbox of object

jira: STUDIO-11625

Signed-off-by: xun.zhang <xun.zhang@bambulab.com>
Change-Id: I4682cd5fe2aef1dc5cd5fd6be33425c7095263eb
(cherry picked from commit 07516d1fecfff7719a60f2c5730bfcbe1958299e)

src/libslic3r/GCode/TimelapsePosPicker.hpp

@@ -64,6 +64,8 @@ namespace Slic3r {
         Polygon m_bed_polygon;
         Point m_plate_offset;
 
+        std::unordered_map<const PrintInstance*, BoundingBoxf3> bbox_cache;
+
         std::optional<Point> m_all_layer_pos;
     };
 }