core: add broadcast (#23965)

* add broadcast_to with tests

* change name

* fix test

* fix implicit type conversion

* replace type of shape with InputArray

* add perf test

* add perf tests which takes care of axis

* v2 from ficus expand

* rename to broadcast

* use randu in place of declare

* doc improvement; smaller scale in perf

* capture get_index by reference

modules/core/include/opencv2/core.hpp

@@ -1118,6 +1118,13 @@ CV_EXPORTS_W void flip(InputArray src, OutputArray dst, int flipCode);
  */
 CV_EXPORTS_W void flipND(InputArray src, OutputArray dst, int axis);
 
+/** @brief Broadcast the given Mat to the given shape.
+ * @param src input array
+ * @param shape target shape. Should be a list of CV_32S numbers. Note that negative values are not supported.
+ * @param dst output array that has the given shape
+ */
+CV_EXPORTS_W void broadcast(InputArray src, InputArray shape, OutputArray dst);
+
 enum RotateFlags {
     ROTATE_90_CLOCKWISE = 0, //!<Rotate 90 degrees clockwise
     ROTATE_180 = 1, //!<Rotate 180 degrees clockwise