get_node() function should have generics in TypeScript

In C#, we are able to use the simplest and nice `` as a shortcut and cleaner version of `(T)` or `as` to convert the Node into other class that is inherited to Node:
```csharp
private Sprite sprite;

public override void _Ready()
{
sprite = GetNode("path/to/sprite");
}
```
But in typescript, we are not allowed to write `` or generics to `get_node()` like in C#. Instead, we use `as` to convert the Node into other class that is inherited to Node.
```typescript
private sprite: godot.Sprite;

public override _ready(): void {
this.sprite = this.get_node('path/to/sprite') as godot.Sprite;
}
```
I'd make a workaround by editing the godot.d.ts but it would be nice if it's built-in to the module.

Commencez dans godot.d.ts et localisez la déclaration de get_node() décrite dans l’issue. Mettez à jour cette déclaration afin que les appelants puissent fournir un générique TypeScript pour le type Node renvoyé, puis vérifiez que l’exemple n’a plus besoin d’un as cast.

Rédigé par le modèle d'indexation à partir du texte de l'issue.