Upgrade bon to 2.2.1

Summary:
As per title, this upgrades us to 2.2.1. One big improvement is that this should [improve rust-analyzer suggestions](https://elastio.github.io/bon/blog/bon-builder-generator-v2-release#experimental-completions-with-rust-analyzer). It should also [compile faster](https://elastio.github.io/bon/blog/bon-builder-v2-1-release).

The primary breaking change (addressed in this diff) is that `&str -> String` conversions are now opt-in.

There's also a new `#[derive(Builder)]` API now exposed by bon, which is destined to replace the raw `#[bon::builder]` macro when a builder is derived for a struct, but the latter isn't deprecated (yet). All new uses of `bon` should use the `#[derive(Builder]` pattern.

Reviewed By: slawlor

Differential Revision: D62687307

fbshipit-source-id: 43873749636f2de7fc05f8552538ff46910506c4