This PR does the following cleanup WRT Cargo.toml:

• Updated Cargo.toml to use workspace settings for version, edition, and license fields (cherry-picked from dist: bump rustup version to 1.28.0 #4041) [1] [2]
• Added workspace linting configurations for Rust idioms and clippy lints. (Cargo.toml, download/Cargo.toml) [1] [2]

This also prepares the repo for its upcoming migration to Rust 2024 by making it easier to enable rust-2024-compatibility across the project. With this change, that will look like:

[workspace.lints.rust]
rust_2018_idioms = { level = "deny", priority = -1 }
rust-2024-compatibility = { level = "warn", priority = -2 }