Add model input size to nvinfer engine name

[bwsw]

When you experiment with different input sizes you want keep engines for them instead of being replaced with the engines generated when the model is built with a new input size.

https://github.com/insight-platform/Savant/blob/ca2d1bda472fcc23f94a71baed76213a1bc26cd9/savant/deepstream/nvinfer/file_config.py#L93-L123