chore: move the go code into a subfolder

apps/api/internal/zerrors/error_test.go

@@ -0,0 +1,19 @@
+package zerrors_test
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/zitadel/zitadel/internal/zerrors"
+)
+
+func TestContains(t *testing.T) {
+	err := errors.New("hello world")
+	world := zerrors.Contains(err, "hello")
+	assert.True(t, world)
+
+	mars := zerrors.Contains(err, "mars")
+	assert.False(t, mars)
+}