[Feature Request] User-based Scoping for Workflows and Automation (Multi-Tenancy Security)

Description 📂 Use Case / Motivation Currently, workflows in Paperless-ngx are globally managed. While they can assign owners based on file paths, there is no strict separation of the automation rules themselves. In a multi-user environment, users should be able to manage their own automation logic without interfering with others. Most importantly, it must be impossible to "intercept" document streams of other users via automation. --- 🛠 Description of Requirements 1. User-Specific Workflow Management • Workflow Ownership: Add an owner field and permissions (view/change) to the Workflow model, similar to how documents are handled. • UI Filtering: Users should only see and manage workflows they own or have been granted access to. This keeps the automation dashboard clean and private. • Path Pre-population: When a user creates a new rule, the "Source Path" should automatically default to their specific consumption folder (e.g., /consume…