Commented Task: Move SqlServerMigrationSqlGenerator and SqlCeMigrationSqlGenerator to their corresponding provider assemblies [1027]

Currently these types live in the EntityFramework.dll assembly but they are provider specific and they should be part of the provider assemblies.

__Need to discuss whether these should move namespace.__
Comments: Fixed by emilcicos in d5de46cbf927d223ca8cbb13cf3397dc84219504