introduce the virtual filesystem everywhere

this unfortunately means I had to cut some features (bye bye commit history! for now)
stuff's not quite 100% working just yet (like branch links, which were and are still broken)
we also don't have content_version impls just yet

crates/treehouse/src/state.rs

@@ -1,4 +1,4 @@
-use std::{collections::HashMap, ops::Range, path::PathBuf};
+use std::{collections::HashMap, ops::Range};
 
 use anyhow::Context;
 use codespan_reporting::{
@@ -6,26 +6,19 @@ use codespan_reporting::{
     files::SimpleFiles,
     term::termcolor::{ColorChoice, StandardStream},
 };
-use serde::Serialize;
 use ulid::Ulid;
 
-use crate::tree::{SemaBranchId, SemaRoots, SemaTree};
-
-#[derive(Debug, Clone, Serialize)]
-pub struct RevisionInfo {
-    pub is_latest: bool,
-    pub number: usize,
-    pub commit: String,
-    pub commit_short: String,
-}
+use crate::{
+    tree::{SemaBranchId, SemaRoots, SemaTree},
+    vfs::VPathBuf,
+};
 
 #[derive(Debug, Clone)]
 pub enum Source {
     Tree {
         input: String,
         tree_path: String,
-        target_path: PathBuf,
-        revision_info: RevisionInfo,
+        target_path: VPathBuf,
     },
     Other(String),
 }
@@ -103,13 +96,6 @@ impl Treehouse {
         }
     }
 
-    pub fn revision_info(&self, file_id: FileId) -> Option<&RevisionInfo> {
-        match self.source(file_id) {
-            Source::Tree { revision_info, .. } => Some(revision_info),
-            Source::Other(_) => None,
-        }
-    }
-
     pub fn next_missingno(&mut self) -> Ulid {
         self.missingno_generator
             .generate()