Consider removing UseSqlServerIdentityColumn and ForSqlServerUseSequenceHiLo

[ajcvickers]

Nobody really knows what they mean, when to use them, or where they are valid.

[ajcvickers]

Note from triage: Consider adding strategy for column-constraint-based Sequence.

[ajcvickers]

May be a breaking change, depending on what we do.

[ajcvickers]

@divega I think we should remove these for 2.0 and then look at bringing them back, possibly with different names and/or other strategies added. Thoughts?

[ajcvickers]

Discussed with @divega and @AndriySvyryd. We are going to make UseSqlServerIdentityColumn work for non key properties without having it trigger client side value generation at all. ForSqlServerUseSequenceHiLo will still throw for non-key columns.

Still need to sync with @bricelam on Migrations behavior.

[bricelam]

Migrations should work fine. If the annotation is on the property, it will create an IDENTITY column.

[AndriySvyryd]

@bricelam That test is for the migration annotation. But now with #8795 the model identity annotation will always be translated to a migrations annotation.