[RAC] Key navigation is broken for nested GridLists

### Provide a general summary of the issue here

After focusing on nested element, pressing arrow down/up will navigate to element in parent list.

### 🤔 Expected Behavior?

Key navigation should be trapped within nested list, till espaced with tab.

### 😯 Current Behavior

Pressing arrow down/up will navigate element in parent list.

### 💁 Possible Solution

_No response_

### 🔦 Context

_No response_

### 🖥️ Steps to Reproduce

https://codesandbox.io/s/throbbing-wind-jflfv7?file=/src/App.js

### Version

"react-aria-components": "1.0.0-beta.0"

### What browsers are you seeing the problem on?

Chrome

### If other, please specify.

_No response_

### What operating system are you using?

MacOS

### 🧢 Your Company/Team

_No response_

### 🕷 Tracking Issue

_No response_