[FEATURE] Support backup/restore functionality at the per-user level

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Support for Backup

Users should be able to seamlessly extract their data, both for backup purposes, but also to facilitate in migrating between services.

Design Requirements

• Versioned: this will facilitate in migration, but also allow users to restore back-ups from previous versions.
• Complete: Everything the user can enter should be in the backup data
• Secure: User data downloads should be encrypted in transit and at rest.
• Easy to Use: Users with limited technical knowledge should be able to work with their user data (this may be accomplished by separate tooling downstream from user backup)

Easiest option:

• Encrypted ZIP folder with table dump CSVs
• Metadata JSON store for user options, versioning, backup date, etc.

Alternatively:

• Store everything in a compressed MessagePack w/ a cryptographic signature
• Add functionality to allow users to upload backups signed from other servers/themselves
• Small, Fast, Lightweight
• Not quite as secure

Alternatively-alternatively

• Chuck everything in Gzipped JSON and make the restore function a massive POST request.
• Still not encrypted at rest w/o additional considerations

Why This is Important

• This forces the developer to guarantee users can access their data through version changes & potential service outages.
• This allows the developer to create server-wide backups with a restore method other than just rolling back the database.
• This gives users the freedom to migrate off of the NoScrum web application with minimal friction
• This provides a necessary data control to users that all web applications should provide.