* [ONNX] Enable cross-compiling and ninja build for onnx_importer

- Change minimum cmake version to 3.11
- Enable cross-compilation of protobuf
- Rewrite ONNX external project into FetchContent
- Fix some issues with ninja build on windows

* Remove -Werror from ONNX CMAKE_CXX_FLAGS

* Unit-test: Link gcpu_backend if NGRAPH_GENERIC_CPU_ENABLE is ON

* Remove overwriting of main CMAKE_CXX_FLAGS from the onnx cmake file

* Fix onnx usage of CMAKE_CXX_FLAGS

* Ignore warning for onnx on windows, restore Windows CXX replacement

* Resolve some problems on OV ci

* Fix missing quotes

* Ignore range-loop-construct warning in onnx

* Just stop be pedantic for onnx

* Remove -Werror as well

* Remove unnecesary code

* style

* Add NGRAPH_API macro to builder::opset1::reorder_axes for OV transformations

* Move NGRAPH_API to header
Co-authored-by: Sang Ik Lee <sang.ik.lee@intel.com>
Co-authored-by: Robert Kimball <robert.kimball@intel.com>
Co-authored-by: Scott Cyphers <scott.cyphers@intel.com>
Co-authored-by: Scott Cyphers <diyessi@users.noreply.github.com>