Draft: [Add] MulPTQ and ScalingMeta MetaOperators

Added MulPTQ Operator and ScalingMeta for PTQ Module

This MR introduces the MulPTQ operator, which essentially implements a MUL operator within a MetaOperator. This operator is required for the PTQ (Post-Training Quantization) module.

Additionally, the ScalingMeta operator has been added to replace the now-deprecated ScalingNodes. The ScalingMeta acts as a meta-operator to handle scaling operations in the PTQ and removing the Scaling Operator (which is not compatible with ONNX).

For more details, please refer to the associated issues: aidge_quantization#43 (closed)