fix(scala): add `for_expression` locals

This change does two main things:

1. Indicate that `(for_expression)`'s introduce a `@scope` (this
   is the scope for the enumerators to be used within the loop).
2. Indicate that the `(identifiers)` within the `(enumerators)` are
   `@definition.var`s.

---

For the following example snippet:

```scala
val fruits = List("apple", "banana", "avocado", "papaya")

val countsToFruits = fruits.groupBy(fruit => fruit.count(_ == 'a'))

for ((count, fruits) <- countsToFruits) {
  println(s"with (fruits) 'a' × $count = $fruits")
}
```

The `count` and `fruits` identifiers are new definitions introduced by
the `for` expressions scope.

0 files changed, 0 insertions, 0 deletions