With this, the user will be able to specify a `getId` function for their screens which returns an unique ID to use for the screen:
```js
<Stack.Screen
name="Profile"
component={ProfileScreen}
getId={({ params }) => params.userId}
/>
```
This is an alternative to the `key` option in `navigate` with several advantages:
- Often users specify a key that's dependent on data already in params, such as `userId`. So it's much easier to specify it one place rather than at every call site.
- Users won't need to deal with generating a unique key for routes manually.
- This will work with other actions such as `push`, and not just navigate.
- With this, it'll be possible to have multiple instances of the screen even if you use `navigate`, which may be desirable in many cases (such as profile screens).
b19f76bfff