Use const modifier when dealing with types

[dcodeIO]

As a follow-up to #3012 (comment), this PR

• Changes the use of auto& introduced in Replace Type::expand() with an iterator-based approach #3061 to const auto& for clarity when dealing with Types

[dcodeIO]

There are more occasions throughout the code base where a similar change might be applicable, yet a quick search for \bauto\b gives 3467 results and I'm hesitating a bit to look at each unless you want me to :) If that's the case, I'd appreciate a quick primer on where to const and where not to const.

[tlively]

yeah no, doing this for just the types is absolutely fine 👍