ObservableObject annotation with record not generating OnPropertyChanged and OnPropertyChanging invokers

### Describe the bug

When using the annotations `[ObservableObject]` and `[ObservableProperty]` in a `class`, it correctly generates (at least) two files. One containing the property which when set calls the functions OnPropertyChanging/OnPropertyChanged and another one containing those functions and the handlers for those events.

If we change the `class` to a `record`, the first file is correctly generated but not the second, causing the OnPropertyChanging/OnPropertyChanged calls not to compile.

Here's an example project: [ObservablePropertyInRecord.zip](https://github.com/CommunityToolkit/dotnet/files/13213997/ObservablePropertyInRecord.zip)

Changing the RecordViewModel from a `record` to a `class` behaves as expected.

### Regression

_No response_

### Steps to reproduce

```text
Example steps to reproduce:

1. Create a `public partial record` with the `[ObservableObject]` annotation
2. Create a variable with the `[ObservableProperty]` annotation
3. Code should not compile and give the errors:

CS0103 The name 'OnPropertyChanging' does not exist in the current context
CS0103 The name 'OnPropertyChanged' does not exist in the current context
```

### Expected behavior

The code generator successfully creates the handlers for a `record` as it does for a `class`.

### Screenshots

ViewModel as a `class`:


Generated code:


ViewModel as a `record`:


Generated code (the second file is missing):


### IDE and version

VS 2022

### IDE version

17.7.6

### Nuget packages

- [ ] CommunityToolkit.Common
- [ ] CommunityToolkit.Diagnostics
- [ ] CommunityToolkit.HighPerformance
- [X] CommunityToolkit.Mvvm (aka MVVM Toolkit)

### Nuget package version(s)

8.2.2

### Additional context

_No response_

### Help us help you

No, just wanted to report this