fix: target build and cargo fmt issues

[gvieira18]

This pull request includes several changes to improve code organization and update the toolchain configuration. The most important changes include switching the Rust toolchain channel from nightly to stable and reorganizing imports across multiple files for better readability and consistency.

Toolchain update:

• rust-toolchain.toml: Changed the Rust toolchain channel from nightly to stable.

Import reorganization:

• src/cluster/scylla_cluster.rs: Reordered imports for ClusterConfig and Compression to improve readability.
• src/helpers/query_parameter.rs: Reorganized imports for RowWriter and SerializationError for consistency.
• src/helpers/query_results.rs: Reordered napi::bindgen_prelude imports for better readability.
• src/session/scylla_session.rs: Moved napi::Either import to maintain consistent import order.
• src/session/topology.rs: Reorganized scylla::transport::ClusterData import for better readability.