feat(tvix/glue): add nixpkgs eval benchmark

This adds a criterion.rs-based testbench into tvix-glue.

It can be invoked by running `cargo bench` from inside the `tvix-glue`
crate.
`target/criterion/report/index.html` contains nice graphs.
It's able to diff against the previous run, so you can invoke `cargo
bench` before and after a certain change to reason about the impact in
evaluation performance.

Currently, we need to create a bunch of Evaluator resources inside the
benchmark loop itself, which is a bit annoying, as it leaks into the
things we benchmark.

This should become better with b/262.

Fixes b/322.

Change-Id: I91656a308887baa1d459ed54d58baae919a4aaf2
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10245
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>

tvix/glue/Cargo.toml

@@ -18,5 +18,10 @@ thiserror = "1.0.38"
 git = "https://github.com/tvlfyi/wu-manber.git"
 
 [dev-dependencies]
+criterion = { version = "0.5", features = ["html_reports"] }
 lazy_static = "1.4.0"
 test-case = "2.2.2"
+
+[[bench]]
+name = "eval"
+harness = false