Consider allowing reverse engineering to generate CLR property defaults based on column defaults

[ajcvickers]

See #9617. For example, if a column State has a default of "WA", then the entity type would be generated as:

public partial class Customer
{
    public string State { get; set; } = "WA";
}

Consider also parsing common SQL defaults, like getdate(), and generating a CLR equivalent.

[ajcvickers]

Triage: We will consider doing this in the future, but:

• Probably in a limited form that doesn't require any complex parsing of SQL
  • In a way that doesn't change the semantics of the default--for example, we wouldn't make getdate() be calculated on the client rather than the server
  • This means probably just simple literals
• It will likely require some form of templating or other customization mechanism for code generation as a prerequisite so that the defaults can be used selectively where wanted.