Integrate ARM KleidiCV as OpenCV HAL

[asmorkalov]

The library source code with license: https://gitlab.arm.com/kleidi/kleidicv/

Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
• The PR is proposed to the proper branch
• There is a reference to the original bug report and related work
• There is accuracy test, performance test and test data in opencv_extra repository, if applicable
  Patch to opencv_extra has the same branch name.
• The feature is well documented and sample code can be built with the project CMake

[asmorkalov]

@opencv-alalek @mplatings I re-integrated KleidiCV with ocv_download. Current branch allows just use -DWITH_KLEIDICV=ON with default HAL version, substitute own URL or set KLEIDICV_SOURCE_PATH to local KleidiCV instance. Please take a look and provide feedback.

[mplatings]

Thanks Alexander. Can you try with this newer KleidiCV version please: https://gitlab.arm.com/kleidi/kleidicv/-/archive/a9971ba8bf1d8b008a32c6ed8fea05cd8eb16748/kleidicv-a9971ba8bf1d8b008a32c6ed8fea05cd8eb16748.tar.gz

[asmorkalov]

Fixed review remarks. Works on HAL priorities.

[asmorkalov]

@opencv-alalek I introduced commit hash as parameter for KleidiCV download as you proposed.
@opencv-alalek @mplatings I returned back KleidiCV as first HAL. Current implementation (macros in KleidiCV) tries to apply KleidiCV first and then fall back to the next possible implementation. CMake does not control priorities, but CMake status message describes it better, if KleidiCV is the first one.

[opencv-alalek]

CMake does not control priorities

That is not true. CMake scrips do that by defining order of used HAL headers.

The last header has the highest priority because it is used like this (example from carotene):

#undef cv_hal_add8u
#define cv_hal_add8u(src1, sz1, src2, sz2, dst, sz, w, h) TEGRA_BINARYOP(CAROTENE_NS::u8, add, src1, sz1, src2, sz2, dst, sz, w, h)

Any previous definitions from other HALs are undefined unconditionally.

[asmorkalov]

Current CMake adds HAL implementation at the beginning of the list. With the CMake chain KleidiCV -> Carotene we have list "carotene;kleidicv". The last one is Kleidi and it defines macros with fallback to previous implementation, Carotene. So current version works as expected.