refactor(tvix/castore): move *Node and Directory to crate root

*Node and Directory are types of the tvix-castore model, not the tvix
DirectoryService model. A DirectoryService only happens to send
Directories.

Move types into individual files in a nodes/ subdirectory, as it's
gotten too cluttered in a single file, and (re-)export all types from
the crate root.

This has the effect that we now cannot poke at private fields directly
from other files inside `crate::directoryservice` (as it's not all in
the same file anymore), but that's a good thing, it now forces us to go
through the proper accessors.

For the same reasons, we currently also need to introduce the `rename`
functions on each *Node directly.

A followup is gonna move the names out of the individual enum kinds, so
we can better represent "unnamed nodes".

Change-Id: Icdb34dcfe454c41c94f2396e8e99973d27db8418
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12199
Reviewed-by: yuka <yuka@yuka.dev>
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

tvix/castore/src/fs/fuse/tests.rs

@@ -15,10 +15,8 @@ use super::FuseDaemon;
 use crate::fs::{TvixStoreFs, XATTR_NAME_BLOB_DIGEST, XATTR_NAME_DIRECTORY_DIGEST};
 use crate::{
     blobservice::{BlobService, MemoryBlobService},
-    directoryservice::{
-        DirectoryNode, DirectoryService, FileNode, MemoryDirectoryService, Node, SymlinkNode,
-    },
-    fixtures,
+    directoryservice::{DirectoryService, MemoryDirectoryService},
+    fixtures, {DirectoryNode, FileNode, Node, SymlinkNode},
 };
 
 const BLOB_A_NAME: &str = "00000000000000000000000000000000-test";

tvix/castore/src/fs/inodes.rs

@@ -4,8 +4,7 @@ use std::time::Duration;
 
 use bytes::Bytes;
 
-use crate::directoryservice::{NamedNode, Node};
-use crate::B3Digest;
+use crate::{B3Digest, NamedNode, Node};
 
 #[derive(Clone, Debug)]
 pub enum InodeData {

tvix/castore/src/fs/mod.rs

@@ -17,8 +17,8 @@ use self::{
 };
 use crate::{
     blobservice::{BlobReader, BlobService},
-    directoryservice::{DirectoryService, NamedNode, Node},
-    B3Digest,
+    directoryservice::DirectoryService,
+    {B3Digest, NamedNode, Node},
 };
 use bstr::ByteVec;
 use bytes::Bytes;

tvix/castore/src/fs/root_nodes.rs

@@ -1,7 +1,6 @@
 use std::collections::BTreeMap;
 
-use crate::{directoryservice::Node, Error};
-use bytes::Bytes;
+use crate::{Error, Node};
 use futures::stream::BoxStream;
 use tonic::async_trait;
 
@@ -23,7 +22,7 @@ pub trait RootNodes: Send + Sync {
 /// the key is the node name.
 impl<T> RootNodes for T
 where
-    T: AsRef<BTreeMap<Bytes, Node>> + Send + Sync,
+    T: AsRef<BTreeMap<bytes::Bytes, Node>> + Send + Sync,
 {
     async fn get_by_basename(&self, name: &[u8]) -> Result<Option<Node>, Error> {
         Ok(self.as_ref().get(name).cloned())