9428e2e25e
[1/N] Implement Arithmetic lint Assuming that https://github.com/rust-lang/rust-clippy/issues/8903 is OK, this PR starts the creation of the `Arithmetic` lint with configurable types. My current struggle to get a rustc review inspired me to create smaller PRs in order to easy review and make merges as fast as possible. So the first step here only moves the `arithmetic.rs` file to `numeric_arithmetic.rs` to make room for the new lint. -- changelog: none