Update base for Update on "[ET-VK][10/n] copy node, aten.repeat"

1. Introduce a `CopyNode` for generic copy-with-offset operations.
2. `aten.repeat` on all dimensions.
2.1 Use `CopyNode` where possible.
2.2. Specialized `repeat_channel` shader to handle packings
3. Update codegen to support `Methods` variant only operations. Need a new route to trigger the dispatch.

Differential Revision: [D56499329](https://our.internmc.facebook.com/intern/diff/D56499329/)

[ghstack-poisoned]

Author: yipjustin