Torch Multi Head Attention
**Is your feature request related to a problem? Please describe.**

I've seen that you are using custom implementation of MHA block - https://github.com/NVIDIA/NeMo/blob/da6d825b8c2fec0a3b8e0d2c33a7600f242db4c1/nemo/collections/asr/parts/submodules/multi_head_attention.py#L108

I think it would be better to use `torch.nn.MultiheadAttention` which is meant to improve the performance of this block (there is FlashAttention now) and torch continues to maintain and update this block while you're doing basic implementation of it.

**Describe the solution you'd like**

I'd like to see an update of models with torch implementation of MHA

https://pytorch.org/docs/stable/generated/torch.nn.MultiheadAttention.html

What do you think about it?
