Add Normalize subgraph, fix Slice, Mul and Expand

* Add Normalize subgraph, support for starts<0 and axis<0 in Slice, Mul broadcasting in the middle and fix Expand's unsqueeze

* remove todos

* remove range-based for loop

* address review comments

* change >> to > > in template

* fix indexation

* fix expand that does nothing

* support PPSeg model for dnn module

* fixed README for CI

* add test case

* fixed bug

* deal with comments

* rm dnn_model_runner

* update test case

* fixed bug for testcase

* update testcase

* Support activations(Sigmoid, Tanh) for LSTM

* fix warning

Split layer dispatch into functions in ONNXImporter

* split layer dispatch into functions

* fixes

* identation and comment fixes

* fix constness

Support non-zero hidden state for LSTM

* fully support non-zero hidden state for LSTM

* check dims of hidden state for LSTM

* fix failed test Test_Model.TextRecognition

* add new tests for LSTM w/ non-zero hidden params
Co-authored-by: NJulie Bareeva <julia.bareeva@xperience.ai>

* Fix bug while loading onnx model in debug

* dnn: fix other .at using
Co-authored-by: NAlexander Alekhin <alexander.a.alekhin@gmail.com>

* Added Steps support in DNN Slice layer

* Added code corrections

* dnn(slice): fix OCL and OCL_FP16 processing

* Fixed bug with constant Div

* Supported constant mul and div for inputs with different shapes

Fix for index error for Reduce Mean

Correct Reduce Mean indexing error

Fixing dnn Resize layer for variable input size

* Fix onnx loading of resize/upsample layers for different opset

* group all DynamicResize tests

* cleaned up scales checks

* Simplify branching

Add support for Conv1D on OpenCV backend

* Add support for Conv1D on OpenCV backend

* disable tests on other targets/backends

* Fix formatting

* Restore comment

* Remove unnecessary flag and fix test logic

* Fix perf test

* fix braces

* Fix indentation, assert check and remove unnecessary condition

* Remove unnecessary changes

* Add test cases for variable weights and bias

* dnn(conv): fallback on OpenCV+CPU instead of failures

* coding style

* Fixed bug in ONNX Mul op

* Replaced node

Fix loading of ONNX models with Resize operation with Opset 11 for newer versions of Pytorch

* Add reproducer for Resize operation from newer versions of Pytorch

* Fix loading of scales parameter for Resize layer

* Change check type for better diagnostic messages

Added Eltwise Layer Support

* Fix ONNX loading in issues opencv#17516, opencv#17531

* Add tests for Linear and Matmul layers

* Disable tests for IE versions lower than 20.4

* Skip unstable tests with OpenCL FP16 on Intel GPU

* Add correct test filtering for OpenCL FP16 tests

* Added ReduceSum to ONNX importer

* Fix comments

* Fix Mul

* Supported convolution with non-const weights

* Fix opencl blobs

* Update tests

* Added ONNX BatchNorm subgraph

* Move removing constant inputs to addConstantNodesForInitializers

* Added initializers to ONNXGraphWrapper