[export_cpp] Slice and Identity nodes for Tiling
## What commit version of aidge do you use
- `aidge_core`: d79c4eb34e327e0b235e6194605d3039bac3b186
- `aidge_export_cpp`: aidge_export_cpp@6fcda722669cf579fbd8b258e31bf2d105ab42e8
## Description
Cf issue aidge_core#280 for the tiling feature, we need identity and slice nodes in order to seamlessly export a tiled model.
I think the identity node is needed though beeing trivial : the graph begins directly with the parallel sliced branches so the input needs to be affected to a single starting node. This way, the identity starting node is needed as input node for the next paralel slice nodes.
I'll try to implement those nodes in a future MR, don't hesitate to tell me if you have a better or more simple solution for the Identity node export.
issue