Merge pull request #25042 from mshabunin:doc-upgrade

Documentation transition to fresh Doxygen #25042

* current Doxygen version is 1.10, but we will use 1.9.8 for now due to issue with snippets (https://github.com/doxygen/doxygen/pull/10584)
* Doxyfile adapted to new version
* MathJax updated to 3.x
* `@relates` instructions removed temporarily due to issue in Doxygen (to avoid warnings)
* refactored matx.hpp - extracted matx.inl.hpp
* opencv_contrib - https://github.com/opencv/opencv_contrib/pull/3638

doc/tutorials/imgproc/pyramids/pyramids.markdown

@@ -43,7 +43,7 @@ Theory
         pyramid (with less resolution)
 -   In this tutorial we'll use the *Gaussian pyramid*.
 
-#### Gaussian Pyramid
+### Gaussian Pyramid
 
 -   Imagine the pyramid as a set of layers in which the higher the layer, the smaller the size.
 
@@ -100,7 +100,7 @@ Explanation
 
 Let's check the general structure of the program:
 
-#### Load an image
+### Load an image
 
 @add_toggle_cpp
 @snippet cpp/tutorial_code/ImgProc/Pyramids/Pyramids.cpp load
@@ -114,7 +114,7 @@ Let's check the general structure of the program:
 @snippet python/tutorial_code/imgProc/Pyramids/pyramids.py load
 @end_toggle
 
-#### Create window
+### Create window
 
 @add_toggle_cpp
 @snippet cpp/tutorial_code/ImgProc/Pyramids/Pyramids.cpp show_image
@@ -128,7 +128,7 @@ Let's check the general structure of the program:
 @snippet python/tutorial_code/imgProc/Pyramids/pyramids.py show_image
 @end_toggle
 
-#### Loop
+### Loop
 
 @add_toggle_cpp
 @snippet cpp/tutorial_code/ImgProc/Pyramids/Pyramids.cpp loop