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/store/src/pathinfoservice/fs/mod.rs

@@ -1,10 +1,9 @@
 use futures::stream::BoxStream;
 use futures::StreamExt;
 use tonic::async_trait;
-use tvix_castore::directoryservice::Node;
 use tvix_castore::fs::{RootNodes, TvixStoreFs};
 use tvix_castore::{blobservice::BlobService, directoryservice::DirectoryService};
-use tvix_castore::{Error, ValidateNodeError};
+use tvix_castore::{Error, Node, ValidateNodeError};
 
 use super::PathInfoService;
 

tvix/store/src/pathinfoservice/grpc.rs

@@ -11,8 +11,8 @@ use tonic::{async_trait, Code};
 use tracing::{instrument, Span};
 use tracing_indicatif::span_ext::IndicatifSpanExt;
 use tvix_castore::composition::{CompositionContext, ServiceBuilder};
-use tvix_castore::directoryservice::Node;
 use tvix_castore::Error;
+use tvix_castore::Node;
 
 /// Connects to a (remote) tvix-store PathInfoService over gRPC.
 #[derive(Clone)]

tvix/store/src/pathinfoservice/lru.rs

@@ -109,7 +109,7 @@ mod test {
             let root_node = p.node.as_mut().unwrap();
             if let castorepb::Node { node: Some(node) } = root_node {
                 let n = node.to_owned();
-                *node = (&tvix_castore::directoryservice::Node::try_from(&n)
+                *node = (&tvix_castore::Node::try_from(&n)
                     .unwrap()
                     .rename("11111111111111111111111111111111-dummy2".into()))
                     .into();