Feature: Implement missing PyAleph API endpoints

[1yam]

This pull request adds support for querying address statistics from the Aleph node API, including filtering and sorting capabilities. It introduces new models and filters for handling address stats, updates the HTTP client to support these queries, and adds comprehensive unit tests for the new functionality.

Address stats query feature:

• Added a new AddressesFilter class to src/aleph/sdk/query/filters.py for filtering and sorting address stats queries, including options for substring filtering and sorting by message type and order.
• Introduced the SortByMessageType enum to specify supported sort fields in address stats queries.
• Implemented the AddressStats and AddressStatsResponse models in src/aleph/sdk/query/responses.py to represent address statistics and the paginated response structure.
• Updated the HTTP client in src/aleph/sdk/client/http.py to add the get_address_stats method, allowing asynchronous retrieval of address statistics with filtering and pagination support. [1] [2]

Testing and validation:

• Added unit tests in tests/unit/test_asynchronous_get.py to verify the new address stats query functionality, including tests for filtered and unfiltered queries, and introduced fixtures in tests/unit/conftest.py to provide mock address stats data and responses. [1] [2] [3]