Created by: wojtuss

With this patch QAT2 procedure supports:

• range-based fake quantize operators,
• channelwise-based fake dequantize operators,
• quantization scales stored in the out_threshold operator attributes.

Also two tests are added for ResNet50 QAT models:

• with range-based input quantization and
• with channel-wise weights quantization.

It is related to https://github.com/PaddlePaddle/Paddle/issues/23346.