ComboBox doesn't validate controlled input

### Provide a general summary of the issue here

1. When `ComboBox` is used inside a `Form`
2. and if the `selectedKey` is `null`, but `inputValue` is given an invalid value
3. the enclosing `Form` doesn't validate that a key is selected

### 🤔 Expected Behavior?

1. When `ComboBox` is used inside a `Form`
2. and if the `selectedKey` is `null`, but `inputValue` is given an invalid value
3. the enclosing `Form` prevents submission of invalid value

### 😯 Current Behavior

as described in the summary

### 💁 Possible Solution

_No response_

### 🔦 Context

_No response_

### 🖥️ Steps to Reproduce

This is just a very simple reproduction. Pressing `submit` button will submit the form although no key is selected:

```tsx

Favorite Animal

Cat
Dog



Submit

```

### Version

"reac-aria-components": "^1.10.1",

### 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_