doc: streamline device path doc between `uefi` and `uefi-raw`

[phip1611]

There are a few duplications and inconsistencies. We should streamline the module documentations and the type documentation.

I'm especially thinking about the device path nodes, device path instances, and device paths in general.

[phip1611]

I've created a dedicated issue because I'm currently not sure if I can cover all aspects I think of as part of #1612