Add Convert operator (a.k.a. Transmitter)

See merge request !57

Update fuseBatchNorm to include ConvDepthWise and MetaOperator containing Conv or ConvDepthWise as an output

Improvements and fixes

See merge request !59

Vit operators

See merge request !47

Change 'int32_t' for 'size_t' as this type is widly used in the whole framework and is made to repesent dimensions

# Conflicts:
#   include/aidge/operator/Slice.hpp
#   src/operator/Slice.cpp

Improve 'GraphView::replace()' for cases where removed operator had multiple outputs also in the GraphView

byding the first tiling prototype

See merge request !58