Migrate allocation table data to blob-registry table - this allows space/blob/list capability to work for older spaces.

[alanshaw]

This is a table rename and a couple of field renames (multihash -> digest and invocation -> cause). For reference, I've listed the current schemas:

• allocation schema:
  • space: string (e.g. did:key:space)
  • multihash: string (e.g. zQm...)
  • size: number (e.g. 101)
  • invocation: string (e.g. baf...ucan - CID of invocation UCAN)
  • insertedAt: string (e.g. 2022-12-24T...)
• blob-registry schema:
  • space: string
  • digest: string
  • size: number
  • cause: string
  • insertedAt: string

Tasks:

• Create blob-registry table and temporarily write to both allocation and blob-registry tables. #272
• Create migration script to migrate allocation table data to blob-registry table. #273
• After production deployment, run migration and then remove old table. #275