[dynamo] mutable local caching to make dynamo faster at tracing mutation (#89170)
Make mutation faster to speed up tracing optimizers, helps with https://github.com/pytorch/torchdynamo/issues/1803
`replace_all` no longer iterates over the entire variable tracker data structure every time a mutation is performed
Each variable tracker internally keeps a set of contained mutable variable trackers, to provide a hint to `replace_all`. This is populated with a call to `apply` from `__post_init__` in the base `VariableTracker`
Pull Request resolved: https://github.com/pytorch/pytorch/pull/89170
Approved by: https://github.com/jansel
