Explicitly specify extensions to include rust-analysis

And change VSCode extension

.vscode/extensions.json

@@ -0,0 +1,5 @@
+{
+    "recommendations": [
+        "matklad.rust-analyzer"
+    ]
+}

flake.nix

@@ -17,10 +17,21 @@
         let pkgs = import nixpkgs {
           inherit system;
           overlays = [ rust-overlay.overlay ];
-        }; in {
+        }; in
+        {
           devShell = pkgs.mkShell {
             nativeBuildInputs = [
-              pkgs.rust-bin.stable.latest.default
+              (pkgs.rust-bin.stable.latest.default.override {
+                extensions = [
+                  "rust-src"
+                  "cargo"
+                  "rustc"
+                  "rls"
+                  "rust-analysis"
+                  "rustfmt"
+                  "clippy"
+                ];
+              })
             ];
           };
         }