Primitive platform identity vocabulary.
`use-platform` stores target-triple-like platform identity as plain data. It does not detect the current platform, call `std::env::consts`, normalize every possible target triple, or replace target-triple crates.
```rust
use use_platform::{Platform, PlatformTriple};
let triple = PlatformTriple::new("aarch64-apple-darwin").unwrap();
let platform = Platform::new(triple);
assert_eq!(platform.to_string(), "aarch64-apple-darwin");
```