This addresses [ENG-10270](https://linear.app/comm/issue/ENG-10270/keyserver-build-failing-with-rust-181).
Changes here:
1. Upgrade everything to Rust 1.85.
2. In order to address [ENG-9892](https://linear.app/comm/issue/ENG-9892/cant-upgrade-to-rust-182):
- We need to bump our Webpack version (see [here](https://github.com/rustwasm/wasm-bindgen/issues/4211#issuecomment-2661563665)).
- We also need to use a higher version of binaryen than the one we're getting from `apt-get`, so I introduced a script to download a later version binary.
- Finally, we need to pass `--reference-types` to `wasm-pack`