Npgsql should ideally build under trimming/AOT without any warnings.

For AOT, one tricky part will likely be advanced types which we don't support because of runtime code generation (arrays, composites). Mapped composites are OK since we have an API that drives them (MapComposite), and we can just mark that API as requiring dynamic code generation (and therefore suppress the warning elsewhere). But arrays have no similar "opt-in" gesture, so it's not clear how we can suppress warnings generated by them.