Query<DateOnly> / Query<TimeOnly> (scalar form) silently return default(T)

Found while probing #2226, but this one is independent of provider and Npgsql version — and it is silent, which makes it the more serious of the two.

With Dapper 2.1.72, a single-column query materialized as a bare DateOnly/TimeOnly returns the default value with no error:

ExecuteScalar<DateOnly> and the member path are fine, so this looks like the Query<T> simple-vs-complex type decision not recognising DateOnly/TimeOnly as scalar types (Type.GetTypeCode reports Object for both) — the member-mapping deserializer then finds nothing to bind on a struct with no settable members and hands back a default instance. The type map entries added in #2051 (DoNotSetFieldValue/UseGetFieldValue) apparently don't reach this decision.

Wrong data with no exception is the worst failure mode available, so flagging it separately from #2226 rather than folding it in.

Start at the Query simple-versus-complex type decision and compare it with the working ExecuteScalar and POCO member paths. Check how the type-map entries from #2051 participate in that decision, then add regression coverage showing DateOnly and TimeOnly scalar queries return their database values rather than default instances.