GAPI (fluid): Erode/Dilate optimization, part 2 (#13319)

* GAPI (fluid): Erode/Dilate optimization: hard-code 3x3 case

* GAPI (fluid): Erode/Dilate optimization: CPU dispatcher

* GAPI (fluid): Erode/Dilate optimization: speed-up 10-15x times with CV_SIMD

* GAPI (fluid): Erode/Dilate optimization: 20-30% speed-up