Editors: format using alejandra

.helix/languages.toml

@@ -0,0 +1,3 @@
+[[language]]
+name = "nix"
+formatter = { command = "alejandra" }

.vscode/settings.json

@@ -1,5 +1,15 @@
 {
     "editor.detectIndentation": true,
     "editor.insertSpaces": true,
-    "editor.defaultFormatter": "jnoortheen.nix-ide"
+    "editor.defaultFormatter": "jnoortheen.nix-ide",
+    "nix.formatterPath": "alejandra",
+    "nix.serverSettings": {
+        "nil": {
+            "formatting": {
+                "command": [
+                    "alejandra"
+                ]
+            }
+        }
+    }
 }