Fix autocorrect for moving constant assignment outside the condition
when the constant is in a namespace, e.g. from:

```ruby
condition ? FOO::BAR = 1 : FOO::BAR = 2

if condition
  ::FOO = 1
else
  ::FOO = 2
end
```

to keep the namespace `Foo::` and the top-level `::` in correction:

```ruby
FOO::BAR = cond? ? 1 : 2

::FOO = if condition
  1
else
  2
end
```