refactor: introduce virtual file system as a central router for source and target data

crates/treehouse/tests/it/vfs/file.rs

@@ -0,0 +1,29 @@
+use treehouse::vfs::{file::BufferedFile, ReadFilesystem, VPath};
+
+fn vfs() -> BufferedFile {
+    BufferedFile::new(b"hewwo :3".to_vec())
+}
+
+#[test]
+fn dir() {
+    let vfs = vfs();
+    assert!(vfs.dir(VPath::ROOT).is_empty());
+}
+
+#[test]
+fn content_version() {
+    let vfs = vfs();
+    assert!(
+        vfs.content_version(VPath::ROOT).is_none(),
+        "content_version is not implemented for BufferedFile for now"
+    );
+}
+
+#[test]
+fn content() {
+    let vfs = vfs();
+    assert_eq!(
+        vfs.content(VPath::ROOT).as_deref(),
+        Some(b"hewwo :3".as_slice()),
+    );
+}