Fix rust 1.72.0 lints/warnings

[etungsten]

Issue number:

N/A

Description of changes:
Preemptively address newly activated lints and warnings in rust 1.72.0

    sources: fix 1.72.0 clippy warnings

    tools: fix 1.72.0 clippy warnings

    chore: explicity set cargo feature resolver version to 2
    
    This gets rid of a warning that comes with rust 1.72.0. This does not
    impact any of our existing crates since they're all on edition 2021.
    
    See https://github.com/rust-lang/cargo/issues/10112

Testing done:
cargo clippy returns no warnings across sources/tools workspaces.
Unit tests pass

Terms of contribution:

By submitting this pull request, I agree that this contribution is dual-licensed under the terms of both the Apache License, version 2.0, and the MIT license.