Update on "[ET-VK][ez] Streamline + fix enabling device extensions"

## Changes

Simplify the logic to construct a linked list of physical device feature structs

When constructing the logical device, construct the linked list of device features to enable instead of using a stored pointer from the constructor of `PhysicalDevice`. The reason is that due to possible moves, the stored pointer may be invalid by the time the `Adapter` instance is constructed. It is safer to reconstruct the device features linked list at the time it is needed.

Differential Revision: [D73438721](https://our.internmc.facebook.com/intern/diff/D73438721/)

[ghstack-poisoned]

Author: SS-JIA