Metadata: Allow indexes and foreign keys to use inherited properties

[AndriySvyryd]

The ModelBuilder should lift the FK or index when there is one declared on the same properties on a derived type

[rowanmiller]

@AndriySvyryd if you don't think this is critical for 7.0.0 then come discuss as we may postpone it

[AndriySvyryd]

7.0.0 and pri0 are appropriate for this

[rowanmiller]

@AndriySvyryd can you add some more details on what this means?

[AndriySvyryd]

Consider

class Base
{
  public int Id { get; set; }
}
class Derived : Base
{
  public string Name { get; set; }
}

You should be able to create an index like this:

modelBuilder.Entity<Derived>().Index(b => new [] { b.Id, b.Name });

Also if you had created an index on the derived entity type:

  modelBuilder.Entity<Derived>().Index(b => new [] { b.Id });

You should be able to override it on base:

  modelBuilder.Entity<Base>().Index(b => new [] { b.Id });

and viceversa.
Same applies to FKs.

[rowanmiller]

@AndriySvyryd can you discuss with folks what we want to do before doing it. Either design meeting, or just in the team room.

[smitpatel]

Partially implementing this for indexes alongwith #700

[smitpatel]

for indexes implemented in bc4609b
Pending for foreignkeys

[smitpatel]

Should base type lift the FK from derived type if defined on same features? or block it?