[Dynamo] Add UserError type (#97705)
To get started the dynamo error message improvement effort, we discussed about adding new user error type which covers cases where the user used something that TorchDynamo doesn't support and there is clear actions they can take.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/97705
Approved by: https://github.com/anijain2305, https://github.com/yanboliang
