refactor: format imports using cargo fmt

[LNSD]

This pull request includes several changes aimed at improving code organization and formatting across multiple files, as well as updates to the GitHub Actions workflow. The most important changes include the reorganization of imports, enabling nightly features for Rust formatting, and updating the GitHub Actions workflow for formatting checks.

Code organization and formatting:

• Reorganized imports to group them more logically and improve readability across multiple files (tap_aggregator/src/aggregator.rs, tap_aggregator/src/main.rs, tap_aggregator/src/server.rs, tap_aggregator/tests/aggregate_test.rs, tap_core/benches/timeline_aggretion_protocol_benchmark.rs, tap_core/src/error.rs, tap_core/src/manager/context/memory.rs, tap_core/src/rav.rs, tap_core/src/rav/request.rs, tap_core/src/receipt/checks.rs, tap_core/src/receipt/receipt_sol.rs, tap_core/src/receipt/received_receipt.rs, tap_core/tests/escrow_test.rs, tap_core/tests/rav_test.rs, tap_core/tests/receipt_test.rs, tap_integration_tests/tests/indexer_mock.rs, tap_integration_tests/tests/showcase.rs). [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20]

GitHub Actions workflow updates:

• Updated the .github/workflows/tests.yml file to use the latest versions of actions/checkout and actions-rust-lang/setup-rust-toolchain, and switched to using the nightly toolchain for formatting checks.

Rust formatting improvements:

• Enabled nightly features required for formatting imports in rustfmt.toml, including unstable_features, imports_granularity, group_imports, and reorder_modules.

[gusinacio]

LGTM