Fix missing case in #299

[escritorio-gustavo]

Goal

In #299, the type_as_infer (now called replace_underscore) function doesn't handle a type Type::Path(TypePath { qself: Some(_), .. }) due to a match on None for the qself field, this PR is a quick fix for that

This allows the following use of as:

#[ts(as = "<_ as Bar>::Baz")]
foo: String

Changes

Removed the match on qself: None and called replace_underscore on qself.ty

Checklist

• [x] I have followed the steps listed in the Contributing guide.
• [x] If necessary, I have added documentation related to the changes made.
• [x] I have added or updated the tests related to the changes made.