Fix template compilation and warnings

Context

Compilation error when building with CUDA 12.6 and GCC 14.2

Modified files

• include/aidge/backend/cuda/data/TensorImpl.hpp
• src/data/TensorImpl.cu
• src/operator/ILayerNormImpl_CUDA_kernels.cu

Detailed major modifications

• Moved enable_if template specialization from parameter to return type which helps the compiler to select the correct implementation.
• Changed factor type to avoid out of bound warning.