Add tag filtering support for automations

[chrisguidry]

Summary

This implements the next part of #16771 by adding comprehensive tag filtering capabilities for automations, following the same pattern used by other entities in Prefect (flows, deployments, etc.).

Changes

• Add tags field to Automation database model with JSON column and migrations
• Update automation schemas (client and server) to include tags field
• Implement AutomationFilterTags with all_, any_, and is_null_ filter options
• Add comprehensive test coverage for all filtering scenarios
• Ensure API compatibility with existing automation functionality

Filtering Options

The filtering supports:

• all_: Return automations that have ALL specified tags (superset match)
• any_: Return automations that have ANY of the specified tags
• is_null_: Return automations with no tags (true) or with tags (false)

Closes #16771

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