enforce key constraints on create & update

turn on key enforcement via config
for primary keys and mongo, this should already be handled by basic schema generation.
for non-primary keys, mongo can enforce key constraint over a single partition with basic schema.
- if we can know we are not sharded, then mongo enforces the key
for all cassandra keys, we need to manage this concern ourselves.
for non-partitioned keys and full enforcement, we need to manage this concern ourselves.
we might be able to work it into the insert/update commands, but if not, we just have to select the key before insert/update.

longevityframework / longevity