Add an eval binary that evaluates our semantic index against CodeSearchNet (#17375)

This PR is the beginning of an evaluation framework for our AI features.
Right now, we're evaluating our semantic search feature against the
[CodeSearchNet](https://github.com/github/CodeSearchNet) code search
dataset. This dataset is very limited (for the most part, only 1 known
good search result per repo) but it has surfaced some problems with our
search already.

Release Notes:

- N/A

---------

Co-authored-by: Jason <jason@zed.dev>
Co-authored-by: Jason Mancuso <7891333+jvmncs@users.noreply.github.com>
Co-authored-by: Nathan <nathan@zed.dev>
Co-authored-by: Richard <richard@zed.dev>

crates/semantic_index/src/project_index.rs

@@ -15,7 +15,14 @@ use log;
 use project::{Project, Worktree, WorktreeId};
 use serde::{Deserialize, Serialize};
 use smol::channel;
-use std::{cmp::Ordering, future::Future, num::NonZeroUsize, ops::Range, path::Path, sync::Arc};
+use std::{
+    cmp::Ordering,
+    future::Future,
+    num::NonZeroUsize,
+    ops::{Range, RangeInclusive},
+    path::{Path, PathBuf},
+    sync::Arc,
+};
 use util::ResultExt;
 
 #[derive(Debug)]
@@ -26,6 +33,14 @@ pub struct SearchResult {
     pub score: f32,
 }
 
+pub struct LoadedSearchResult {
+    pub path: Arc<Path>,
+    pub range: Range<usize>,
+    pub full_path: PathBuf,
+    pub file_content: String,
+    pub row_range: RangeInclusive<u32>,
+}
+
 pub struct WorktreeSearchResult {
     pub worktree_id: WorktreeId,
     pub path: Arc<Path>,