Added async implementation of MultiDBClient

[vladvildanov]

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Description of change

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[Copilot]

Pull Request Overview

This PR adds async implementation of MultiDBClient to support asynchronous operations with multiple Redis databases. The implementation provides circuit breaker patterns, health checks, and failure detection in an async context.

• Replaces SyncCircuitBreaker with unified CircuitBreaker interface across all components
• Adds complete async multidb module with client, configuration, command execution, and health checks
• Extends background scheduler with async recurring task support

Reviewed Changes

Copilot reviewed 29 out of 32 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
tests/test_multidb/test_config.py	Updates circuit breaker imports and removes empty lines
tests/test_multidb/test_client.py	Removes unnecessary blank lines in test assertions
tests/test_multidb/test_circuit.py	Updates circuit breaker type references in imports and callbacks
tests/test_multidb/conftest.py	Updates all mock circuit breaker references to unified type
tests/test_background.py	Adds async test coverage for recurring background tasks
tests/test_asyncio/	Comprehensive test suite for async multidb components
redis/utils.py	Adds async dummy failure function for retry operations
redis/multidb/	Updates circuit breaker interface and removes sync-specific types
redis/event.py	Fixes async lock usage and adds async event types
redis/background.py	Adds async recurring task scheduling capability
redis/asyncio/multidb/	Complete async implementation of multidb functionality

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[petyaslavova]

Overall LGTM. You just need to fix the minor formatting issues reported by Copilot and it will be ready for merging.