INT8 conv operator implementation with NCHWc data layout for Intel machines (#1680)

* Int8 implementation for convolution operator on Intel Skylake

* Int8 implementation for convolution operator on Intel Skylake

* PR changes

* PR changes

* PR changes

* Fixing an error

* Fixing an error

* Minor typos fix

* Minor typos fix

* Removing the broadcast16 CPP code. Using astype feature instead

* Replacing constant by variable name num_elements_intel

* Name fixes and tensorize update rule updated

* Fixing the bug about checking skylake

* Replacing bitcast with reinterpret

* Isolating INT8 and FP32 schedules to ease out future AutoTVM PR merge

* Putting check_skylake function in the x86 directory

* Added documentation and organizing files to better locations

* Tensor intrin renaming. Avoid code duplication for intrin by kernel reshaping