Fix problems in checking that a constructor is uninhabited for exhaustive match checking

[Alex1005a]

1. If the field with bottom type is lazy, then the constructor is inhabited.
2. Now it is taken into account that the type member can be Nothing and the field can be this type member.
3. The check has been moved to the inhabited function, allowing some changes to be reverted from Do not consider uninhabited constructors when performing exhaustive match checking #21750

I was also thinking about making the check recursive, i.e. checking that all fields are inhabited. This could cause problems with cycles and performance, so I'm not sure whether to do it.