refactor(nix-compat) Make nixhash_* mods hierarchical

They can go under `nixhash`

Change-Id: Ia15835c57130b66d58f5df80ae9595dceee00941
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8408
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

tvix/nix-compat/src/lib.rs

@@ -2,6 +2,4 @@ pub mod derivation;
 pub mod nar;
 pub mod nixbase32;
 pub mod nixhash;
-mod nixhash_algos;
-mod nixhash_with_mode;
 pub mod store_path;

tvix/nix-compat/src/nixhash/mod.rs

@@ -2,8 +2,11 @@ use crate::nixbase32;
 use data_encoding::{BASE64, BASE64_NOPAD, HEXLOWER};
 use thiserror::Error;
 
-pub use crate::nixhash_algos::HashAlgo;
-pub use crate::nixhash_with_mode::NixHashWithMode;
+mod algos;
+mod with_mode;
+
+pub use algos::HashAlgo;
+pub use with_mode::NixHashWithMode;
 
 /// Nix allows specifying hashes in various encodings, and magically just
 /// derives the encoding.