Modify handling of quoted non-expanded string literal

Quoted non-expanded literal strings, `%q!***!`, should not be expanded and should be able to include nested parenthesis.

I think that the following is expected.

```ruby
a = "1"
puts %q(#{a})
# => #{a}

puts %q((ab))
# => (ab)

puts %q(a(b\)c))
# => a(b)c)
```