Tests for new creation flow

[danielroney]

Work Item

This is a sub task of Offline blob uploads Phase 2 - Support "offline" blob uploads with detached container #6128

Approach

• Implement hook for uploading blobs on Container.attach()
• As detached blobs upload, add their before/after URLs to a table and reclaim detached storage.
• Use the table to resolve requests for "before" URLs.
• Add snapshot/load APIs to IDetachedBlobStorage
• Include blob redirection table in summary.