search: New old search implementation (#39956)

This is an in-progress work on changing how task scheduler affects
performance of project search. Instead of relying on tasks being
executed at a discretion of the task scheduler, we want to experiment
with having a set of "agents" that prioritize driving in-progress
project search matches to completion over pushing the whole thing to
completion. This should hopefully significantly improve throughput &
latency of project search.

Release Notes:

- Improved project search performance

---------

Co-authored-by: Smit Barmase <smit@zed.dev>
Co-authored-by: Smit Barmase <heysmitbarmase@gmail.com>

Cargo.lock

@@ -12890,6 +12890,23 @@ dependencies = [
  "zlog",
 ]
 
+[[package]]
+name = "project_benchmarks"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "clap",
+ "client",
+ "futures 0.3.31",
+ "gpui",
+ "http_client",
+ "language",
+ "node_runtime",
+ "project",
+ "settings",
+ "watch",
+]
+
 [[package]]
 name = "project_panel"
 version = "0.1.0"
@@ -20590,6 +20607,16 @@ dependencies = [
  "zlog",
 ]
 
+[[package]]
+name = "worktree_benchmarks"
+version = "0.1.0"
+dependencies = [
+ "fs",
+ "gpui",
+ "settings",
+ "worktree",
+]
+
 [[package]]
 name = "writeable"
 version = "0.6.1"