feat(eventstore): Precondition (#69)

* start org

* refactor(eventstore): filter in sql for querier

* feat(eventstore): Aggregate precondition

preconditions are checked right before insert. Insert is still transaction save

* feat(eventstore): check preconditions in repository

* test(eventstore): test precondition in models

* test(eventstore): precondition-tests

* refactor(eventstore): querier as type

* fix(precondition): rename validation from precondition to validation

* test(eventstore): isErr func instead of wantErr bool

* fix: delete org files

* remove comment

Co-authored-by: Livio Amstutz <livio.a@gmail.com>

internal/errors/caos_error.go

@@ -46,3 +46,8 @@ func (err *CaosError) GetMessage() string {
 func (err *CaosError) GetID() string {
 	return err.ID
 }
+
+func (err *CaosError) Is(target error) bool {
+	_, ok := target.(*CaosError)
+	return ok
+}