shell: Add llvm-tools-preview and cargo-llvm-cov

Author: the-mikedavis

rust-toolchain.toml

@@ -1,3 +1,3 @@
 [toolchain]
 channel = "1.70.0"
-components = ["rustfmt", "rust-src"]
+components = ["rustfmt", "rust-src", "llvm-tools-preview"]

shell.nix

@@ -5,10 +5,11 @@ in
 pkgs.mkShell {
   nativeBuildInputs = with pkgs; [
     (toolchain.override {
-      extensions = ["rust-src" "clippy"];
+      extensions = ["rust-src" "clippy" "llvm-tools-preview"];
     })
     rust-analyzer
     cargo-flamegraph
+    cargo-llvm-cov
   ];
   RUST_BACKTRACE = "1";
 }