feat(tvix/glue): contextful derivation

We calculate the input context by performing the union of context
over all input of the derivation.

Then, we just pass the rest of it to the remaining machinery.

Finally, we re-emit an `outPath` and a `drvPath` containing the expected
contexts.

Change-Id: I74905fb258b5bee8b08d1208c9eb87f51b92a890
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10436
Autosubmit: raitobezarius <tvl@lahfa.xyz>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI

tvix/cli/src/main.rs

@@ -91,15 +91,12 @@ fn interpret(code: &str, path: Option<PathBuf>, args: &Args, explain: bool) -> b
     let known_paths: Rc<RefCell<KnownPaths>> = Default::default();
     add_derivation_builtins(&mut eval, known_paths.clone());
     configure_nix_path(&mut eval, &args.nix_search_path);
-    eval.io_handle = Box::new(tvix_glue::tvix_io::TvixIO::new(
-        known_paths,
-        TvixStoreIO::new(
-            blob_service,
-            directory_service,
-            path_info_service.into(), // we need an Arc<_> here.
-            tokio_runtime.handle().clone(),
-        ),
-    ));
+    eval.io_handle = Box::new(tvix_glue::tvix_io::TvixIO::new(TvixStoreIO::new(
+        blob_service,
+        directory_service,
+        path_info_service.into(), // we need an Arc<_> here.
+        tokio_runtime.handle().clone(),
+    )));
 
     let source_map = eval.source_map();
     let result = {