[Feature]: Transformations with input sandbox

[aldbr]

User Story

As a powerful user, I want to upload my private payload (closed source code) in an input sandbox that can be reused within a transformation, so that I don't have to publicly share my code.

Feature Description

This is based on a use case we have in LHCb.

Definition of Done

• Feature works as expected
• Tests that the input sandbox can be reused by many different jobs
• Documentation

Alternatives Considered

No response

Related Issues

No response

Additional Context

No response