[Add] first MetaOperator implementation: PaddedConv

Context

This implementation works but is not fed to the Registrar system because it is less efficient than the combination of Pad->Conv in MetaOperator with an optimized non-padded convolution.

Modified files

• PaddedConvImpl.hpp
• PaddedConvImpl.cpp
• PaddedConvImpl_kernel.hpp

Detailed major modifications

Add first functional metaoperator implementation.

TODO

• Optimize the implementation inference time