* Unified Storage: Return an already exists error
When inserting a resource that already exists (i.e. race condition), we can safely catch UNIQUE constraint violations
and transform them into a `k8s.io/apimachinery/pkg/api/errors` error that stands the test of `errors.IsAlreadyExists`.
* feat: clarify existing conflict error
* chore: make update-workspace
* feat: make new package for backend error
* fix: assign dependency owner
* feat: use dialect for checking error type
* chore: go generate
* revert: to 5af369166d6
