Heterogeneous Data Source Exploration and Tracking

[gioialm]

Summary

This PR adds the frontend support corresponding to the backend implementation for MongoDB sources, automatic schema exploration, refresh operations, and source materializations. It introduces new user interfaces for creating materializations, refreshing Sources and Source entities, and presenting detected schema changes.

Changes

Refresh Operations

Entity Refresh

• Upgraded the existing refresh action in the entity view to perform a schema refresh.
• Displays a summary of all detected schema changes after each refresh.

Source Refresh

• Added a new refresh action to the Source entity sidebar.
• Refreshes the complete Source and displays a summary of all detected changes.

Source Materializations

• Added a new Materializations tab to the Source schema view.
• Supports creating both independent and synchronized materializations for relational tables and MongoDB collections.
• Added dialogs and workflows corresponding to the backend implementation.

Tests

• Entity and Source refresh workflows.
• Refresh summary dialogs.
• Materialization creation workflows.
• UI integration for relational and MongoDB sources.