Fix tensor data type in optimizer (SGD, Adam)

Context

It is not possible to use an Optimizer (SGD, Adam) for a data type different from float32.

Detailed major modifications

Use the setDataType method for all tensors involved in Optimizer.

assigned to @oantoni

requested review from @olivierbichler

added Fix 🔥🔥 label

changed milestone to %aidge v0.6.0

added Enhancement ⭐ label and removed Fix 🔥🔥 label

approved this merge request

mentioned in commit 58f7c200

merged