Support for proxying frozen dataclasses (#134846)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/133858
Details: Previously Dynamo would treat dataclasses as UserDefinedVariables. This was non-desirable if we would like to proxy the value into the graph, which is needed for TensorSubclassMetadata. To rectify this, frozen dataclasses are now able to be proxied similarly to NamedTuples. We require the object to be frozen, because if arbitrary mutation were allowed, we would need to replay those mutations in the graph after construction of the object.
For tracing construction of the variable, the generated `__init__` for the dataclass uses `object.__setattr__` because frozen dataclasses throw errors on the usual `__setattr__` invocation. With this treatment, no special handling is needed in dynamo for frozen dataclass construction.
X-link: https://github.com/pytorch/pytorch/pull/134846
Approved by: https://github.com/bdhirsh, https://github.com/anijain2305
Reviewed By: izaitsevfb
Differential Revision: D62214715
Pulled By: mlazos
fbshipit-source-id: 5d23a33adc34ae7522a85d021cfbef0e77ed824a
