Auto merge of #137424 - Ayush1325:uefi-path-node, r=nicholasbishop,cuviper

uefi: helpers: Add DevicePathNode abstractions

- UEFI device path is a series of nodes layed out in a contiguous memory region. So it makes sense to use Iterator abstraction for modeling DevicePaths
- This PR has been split off from #135368 for easier review. The allow dead_code will be removed in #135368

cc `@nicholasbishop`

Author: bors