ComponentDispatcher.(Enter|Leave)ThreadModal should be called by System.Windows.MessageBox.Show

### Description

Window.ShowDialog calls (Enter|Leave)ThreadModal but MessageBox.Show does not. In windows forms, Application.(Enter|Leave)ThreadModal was called by both.

### Reproduction Steps

```
ComponentDispatcher.EnterThreadModal += (o, e) => { whatever(); };
MessageBox.Show("blah");
```

### Expected behavior

`whatever()` should be called

### Actual behavior

it's not

### Regression?

_No response_

### Known Workarounds

_No response_

### Impact

_No response_

### Configuration

_No response_

### Other information

_No response_