Resolves #13375

RGB to/from Gray rewritten to wide intrinsics (#13379)

* 5x5 to RGB added

* RGB25x5 added

* Gray2RGB added

* Gray2RGB5x5 added

* vx_set moved out of loops

* RGB5x52Gray added

* RGB2Gray written

* warnings fixed (int -> (u)short conversion)

* warning fixed

* warning fixed

* "i < n-vsize+1" to "i <= n-vsize"

* RGBA2mRGBA vectorized

* try to fix ARM builds

* fixed ARM build for RGB2RGB5x5

* mRGBA2RGBA: saturation, vectorization

* fixed CL implementation of mRGBA2RGBA (saturation added)

* added performance test for compareHist

* compareHist reworked to use wide universal intrinsics

* Disabled vectorization for CV_COMP_CORREL and CV_COMP_BHATTACHARYYA if f64 is unsupported

- use "random" area on input image
- avoid duplicate cases

'ksize' is not updated with 'kernel'

This reverts commit 7349b8f5 (partially).

* Updated boxFilter implementations to use wide universal intrinsics

* boxFilter implementation moved to separate file

* Replaced ROUNDUP macro with roundUp() function

* avoid rounding errors

* imgproc: replace condition in matchTemplate

* Update imgproc.hpp

* update color conversion codes

* RGB2RGB initially rewritten

* NEON impl removed

* templated version added for ushort, float

* data copying allowed for RGB2RGB

* inplace processing fixed

* fields to local vars

* no zeroupper until it's fixed

* vx_cleanup() added back

* Updated ICV packages and IPP integration

* core(test): minMaxIdx IPP regression test

* core(ipp): workaround minMaxIdx problem

* core(ipp): workaround meanStdDev() CV_32FC3 buffer overrun

* Returned semicolon after CV_INSTRUMENT_REGION_IPP()

Exceptions caught by value incur needless cost in C++, most of them can
be caught by const-reference, especially as nearly none are actually
used. This could allow compiler generate a slightly more efficient code.

  - improve cpu dispatching calls to allow more SIMD extentions
    (SSE4.1, AVX2, VSX)
  - wide universal intrinsics
  - replace dummy v_expand with v_expand_low
  - replace v_expand + v_mul_wrap with v_mul_expand for product accumulate operations
  - use FMA for accumulate operations
  - add mask and more types to accumulate's performance tests

  - redefine 16-bit multiply operator to perform saturating multiply
    instead of non-saturating multiply
  - implement 8-bit multiply operator to perform saturating multiply
  - implement v_mul_wrap() for 8-bit, 16-bit non-saturating multiply
  - improve performance of v_mul_hi() for VSX
  - update intrin tests with new changes
  - replace unv 16-bit multiplication operator with v_mul_wrap due behavior changes

  - Several improvements depend on vpisarev review

    * initial forward declarations for universal intrinsics
    * move emulating SSE intrinsics into separate file
    * implement v_mul_expand for 8-bit
    * reimplement saturating multiply using v_mul_expand + v_pack
    * map v_expand, v_load_expand, v_load_expand_q to sse4.1
    * fix overflow avx2::v_pack(uint32)
    * implement two universal intrinsics v_expand_low and v_expand_high

* Add documentation for cvtColorTwoPlane

* Change brief and add links