Taint detection does not work for encapsulated strings (echo "$unsafe";)

Observed: No TaintedInput is emitted, but it would be emitted if the quotes are removed
Expected: TaintedInput is emitted 

`$pdo->exec("select * from users where name='" . $name . "'")` in https://psalm.dev/docs/security_analysis/ suggests taint detection already works for concatenation but not encapsulation

```php
<?php

$unsafe = $_GET['unsafe'];
echo "$unsafe";
```