[quant][pt2] Handle no conv bias in prepare QAT fusion (#100610)
Summary: This commit adds support for conv + BN fusion for the
case where conv has no bias. Since the replacement patterns with
and without conv bias are substantially different, we perform the
replacement for each of these two cases separately.
Test Plan:
python test/test_quantization.py TestQuantizePT2E.test_prepare_qat_conv_bn_fusion_no_conv_bias
Reviewers: jerryzh168, kimishpatel
Differential Revision: [D45743510](https://our.internmc.facebook.com/intern/diff/D45743510)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/100610
Approved by: https://github.com/jerryzh168
