Pre RFC / Feature Request: (De)structuring

As far as I know, there is no syntactic meaning in glimmer for `{ }` (single curlies).
So, without diving in at trying to implement this myself, it seems like we have room to implement something like the following:

```hbs
{{!-- Before --}}

{{!-- After --}}

```
and
```hbs
{{!-- Before --}}

{{@text}}

{{!-- After -- I don't think this is the right way to do this, cause it's semantically weird --}}

{{@text}}

```

Thoughts?