Types: Object data format should allow null values for `y` for Line Charts

### Expected behavior

According to the [docs](https://www.chartjs.org/docs/latest/general/data-structures.html#object), `null` values are allowed for skipped values for Line Charts. The following code should pass the type check:

```ts
import { Chart } from 'chart.js';

var ctx = document.getElementById("myChart") as HTMLCanvasElement;
var myChart = new Chart<'line'>(ctx, {
// Config example from documentation
type: 'line',
data: {
datasets: [{
data: [{x: 10, y: 20}, {x: 15, y: null}, {x: 20, y: 10}]
// ~~~~ null value here, should be ok
}]
}
});
```

### Current behavior

TypeScript error: `Type 'null' is not assignable to type 'number'.`

### Reproducible sample

https://www.typescriptlang.org/play/?ssl=11&ssc=4&pln=10&pc=4#code/JYWwDg9gTgLgBAbzgYQBYENZwL5wGZQQhwDkAxhrAHQBWAziQNwCwAUGwG6ZxkwAecALxwAJhDIBXEAFMAdjCoBzaTACiAG2kz5AIQCeASREAKAEQg9aTDFMBKOOjpwAEgBUAsgBlk6WVzoaWnIwLKxcUHAWVljCstIA7iiUMAA8JOrAcSQAfMa8fAA0iGxwcDB6YNIAXKQZWQUlougw6DUIjaUizY4qdDUA2u2spSNNLQMIfDUAjAAMRXo1AEyz2EWTMwCsCzWyEurqa4hTcCs7cHPYALodODfDOGzYtoxAA

### Optional extra steps/info to reproduce

Generic type should be specified for Chart constructor: `new Chart<'line'>(...)`. There are no errors without it.

### Possible solution

_No response_

### Context

_No response_

### chart.js version

v4.4.7

### Browser name and version

_No response_

### Link to your project

_No response_