Update formatting for stable Rust

[bushrat011899]

Objective

The current source code of this project has many pending formatting changes that would be implemented by cargo fmt. This makes future PRs challenging as the instinctual action of running cargo fmt will create many unrelated changes.

Solution

• Added a small number of targeted formatting exceptions (see the first commit Add fmt exceptions)
• Ran cargo fmt using the current stable version of Rust (1.86.0) (see the second commit cargo fmt)