Flatten snapshot middleware to be much simpler (#324)

* First take at flattening middleware for simpler code and better perf

* Undo debug prints

* Fix using wrong path in snapshot_from_vfs

* Disable some broken tests

* Re-enable (mistakenly?) disabled CSV test

* Fix some tests

* Update project file tests

* Fix benchmark

src/snapshot_middleware/middleware.rs

@@ -1,13 +1,5 @@
-use std::path::Path;
-
-use memofs::Vfs;
-
-use crate::snapshot::{InstanceContext, InstanceSnapshot};
+use crate::snapshot::InstanceSnapshot;
 
 use super::error::SnapshotError;
 
 pub type SnapshotInstanceResult = Result<Option<InstanceSnapshot>, SnapshotError>;
-
-pub trait SnapshotMiddleware {
-    fn from_vfs(context: &InstanceContext, vfs: &Vfs, path: &Path) -> SnapshotInstanceResult;
-}