Migration scripts

[lmarini]

Develop migration scripts from v1 to v2.

• Could work directly with mongo or using the pydantic models to simplify writing to v2 database
• We should be able to migrate path on disk of blobs directly to s3

[tcnichol]

As of now, everything migrates except the spaces to groups portion. That is blocked by a v1 issue solved in this pull request.

clowder-framework/clowder#453