maint: Move to /rust/* to /

This makes it easier for tooling to find the Rust stuff.
Rust/non-rust is not a useful distinction in this repo anymore anyway.

rust/nix-bindings-store/src/derivation.rs

@@ -1,25 +0,0 @@
-#![cfg(nix_at_least = "2.33")]
-
-use nix_bindings_bindgen_raw as raw;
-use std::ptr::NonNull;
-
-/// A Nix derivation
-///
-/// **Requires Nix 2.33 or later.**
-pub struct Derivation {
-    pub(crate) inner: NonNull<raw::derivation>,
-}
-
-impl Derivation {
-    pub(crate) fn new_raw(inner: NonNull<raw::derivation>) -> Self {
-        Derivation { inner }
-    }
-}
-
-impl Drop for Derivation {
-    fn drop(&mut self) {
-        unsafe {
-            raw::derivation_free(self.inner.as_ptr());
-        }
-    }
-}