Experimenting with more structured ways to handle command-line input/output in Rust

Create `fluent_embed_runtime` crate

Currently a simple re-export of runtime dependencies and Localize trait, which should be extended to have default implementations for dates/times, file sizes etc.

Created by  finchie  on July 12, 2024
HHJDRLLNN36UNIA7STAXEEVBCEMPJNB7SJQOS3TJLLYN4AEZ4MHQC
Change contents