fix(react): Nav unmounts component while invoking popTo or popToRoot (#27821)

Issue number: Resolves #27798

---------

## What is the current behavior

React IonNav component's views are missing keys, leading to unnecessary
duplicate mounting of components.


## What is the new behavior?
- Adds key to views of React IonNav component.

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

---------

Co-authored-by: Sean Perkins <sean@ionic.io>