feat(tvix/store): add mount command to entrypoint and fuse mod

`tvix-store mount PATH` will mount the tvix-store to the given path.

Change-Id: Icb82a6b3cb8a22eec856c375a28ae5580403833f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8665
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>

tvix/store/src/fuse/mod.rs

@@ -0,0 +1,24 @@
+use crate::{
+    blobservice::BlobService, directoryservice::DirectoryService, pathinfoservice::PathInfoService,
+};
+
+pub struct FUSE<BS: BlobService, DS: DirectoryService, PS: PathInfoService> {
+    blob_service: BS,
+    directory_service: DS,
+    path_info_service: PS,
+}
+
+impl<BS: BlobService, DS: DirectoryService, PS: PathInfoService> FUSE<BS, DS, PS> {
+    pub fn new(path_info_service: PS, directory_service: DS, blob_service: BS) -> Self {
+        Self {
+            blob_service,
+            path_info_service,
+            directory_service,
+        }
+    }
+}
+
+impl<BS: BlobService, DS: DirectoryService, PS: PathInfoService> fuser::Filesystem
+    for FUSE<BS, DS, PS>
+{
+}