magiskboot: migrate check_fmt to Rust

Migrate check_fmt and guess_lzma to Rust in format.rs.

Assisted-by: Gemini 3.6 Flash
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f