Support FakeTensor with FlatParameter (#101987)
In this PR we turn FlatParameter into a virtual tensor subclass
which doesn't actually ever get instantiated: __new__ will create
a Parameter instead (or a FakeTensor, if necessary).
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/101987
Approved by: https://github.com/awgu, https://github.com/eellison
