issue 13018: translate does not accept immutable or const AAs

https://issues.dlang.org/show_bug.cgi?id=13018
I don't get the exact problem here, in any case `manually unrolled because ...` better to add a problematic line or link bug report.
This works just fine:
```d
alias TypeTuple(T...) = T;
void main(){

    alias Types = TypeTuple!(dchar[dchar], const dchar[dchar], immutable dchar[dchar]);
    foreach(T; Types) {
        T t =  ['h' : 'q', 'l' : '5'];
    }
}
```