Subclass view fake-ification via reified ViewFuncs (#118405)
This PR:
* Uses reified ViewFuncs to swap in fake tensors / symbolic SymInts for view replay during subclass view fake-ification
* Enables automatic dynamic on view bases -> fakeifies according to the resultant symbolic context instead of the old "all-static" approach
* Covers the following view types:
* subclass -> dense
* dense -> subclass
* subclass -> subclass
* Dense -> dense views are handled the old way via an `as_strided()` call, as it's likely there is no view func available
Differential Revision: [D54269082](https://our.internmc.facebook.com/intern/diff/D54269082)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/118405
Approved by: https://github.com/ezyang
