Support for make_date for new DateTime

[richardsheppard-avalara]

Looking for support translating new DateTime() into make_date in postgresql.

Currently seeing this exception when trying to do so. We are having to apply the date filter in memory right now.

The LINQ expression 'DbSet<Test>
    .Where(f => new DateTime(
        (int)f.Year, 
        (int)f.Month, 
        1
    ))' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to either AsEnumerable(), AsAsyncEnumerable(), ToList(), or ToListAsync(). See https://go.microsoft.com/fwlink/?linkid=2101038 for more information.
   at

Dotnet Core: 3.1
Npgsql.EntityFrameworkCore.PostgreSQL: 3.1.0

[roji]

Similar to #1020 which is about NodaTime, but unlike that issue we're not blocked by dotnet/efcore#18797 since we're not a plugin.

SO: https://stackoverflow.com/questions/59656286/how-to-filter-datetime-with-three-fields-day-month-year-in-ef-core-and-postgresq/59792245#59792245