Add Min layer to CPU, OpenCL, Halide, Inference Engine, NGraph and CUDA

[rogday]

Merge with extra: opencv/opencv_extra#908

Related: #20438

opencv_extra=min

force_builders=Custom,Custom Win,Custom Mac
build_image:Custom=ubuntu-openvino-2021.4.0:20.04
build_image:Custom Win=openvino-2021.4.0
build_image:Custom Mac=openvino-2021.4.0

test_modules:Custom=dnn,python2,python3,java
test_modules:Custom Win=dnn,python2,python3,java
test_modules:Custom Mac=dnn,python2,python3,java

buildworker:Custom=linux-1
test_opencl:Custom=ON
test_bigdata:Custom=1
test_filter:Custom=*

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 other license that is incompatible with OpenCV
• The PR is proposed to proper branch
• There is reference to 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

[alalek]

Looks good to me 👍

[alalek]

It make sense to create another PR to master branch as this PR to 3.4 is ready.
(which includes these changes or wait for "merge 3.4" PR (ETA: end of week))

[YashasSamaga]

Maybe fusions tests should be enabled for min op:

opencv/modules/dnn/test/test_layers.cpp

Lines 2340 to 2344 in c3ac834

	static testing::internal::ParamGenerator<std::string> eltwiseOpList()
	{
	// TODO: automate list generation
	return Values("sum", "max", "prod", "div");
	}

They might help identify accidental fusions.

[sergei-sl]

Looks good to me 👍

[sl-sergei]

Approve from the correct account