test(05-04): add failing tests for attach File, Thumb, and bucket

- ThumbFilename/PartitionDirectory/File.Thumb behavior tests
- OpenBucket fail-loud and memblob tests
- Migrate empty plugin list must create system_files

lagoon/attach/bucket.go

@@ -0,0 +1,22 @@
+package attach
+
+import (
+	"context"
+	"fmt"
+
+	"git.golem15.com/golem15/summercms/backpack"
+	"git.golem15.com/golem15/summercms/compass"
+	"gocloud.dev/blob"
+	_ "gocloud.dev/blob/fileblob"
+	_ "gocloud.dev/blob/memblob"
+)
+
+func OpenBucket(ctx context.Context, cfg *compass.Config) (*blob.Bucket, error) {
+	return nil, fmt.Errorf("attach: bucket not implemented")
+}
+
+func Publish(app *backpack.App, bucket *blob.Bucket) error {
+	return fmt.Errorf("attach: publish not implemented")
+}
+
+func PublicPathPrefix() string { return "" }