Remove ISchematized interface

[Zruty0]

ISchematized interface is not consumed anywhere: we can safely remove it.

While we are at it, we could also rename IRowToRowMapper.Schema to OutputSchema to match InputSchema.

[wschin]

I don't see a Schema in IRowToRowMapper after removing ISchematized. Can ISchematized be removed?

[Update] For whatever classes Schema provided by ISchematized is used, we add a new Schema to those classes.