move gen_aten and gen_aten_hip into shared build structure
Pull Request resolved: https://github.com/pytorch/pytorch/pull/77751
This requires two changes to rule generation:
* pulling the cpu static dispatch prediction into the rules
* disabling the Bazel-style generated file aliases
Differential Revision: [D36481918](https://our.internmc.facebook.com/intern/diff/D36481918/)
**NOTE FOR REVIEWERS**: This PR has internal Facebook specific changes or comments, please review them on [Phabricator](https://our.internmc.facebook.com/intern/diff/D36481918/)!
Approved by: https://github.com/kit1980, https://github.com/seemethere
Author
Michael Andreas Dagitses
