refactor: removing needless module complexity

modules/home/programs/nixvim/plugins/rustaceanvim.nix

@@ -0,0 +1,29 @@
+{
+  lib,
+  config,
+  ...
+}:
+with lib; let
+  cfg = config.home.devtools.nixvim.plugins.rustaceanvim;
+in {
+  options.home.devtools.nixvim.plugins.rustaceanvim = {
+    enable = mkEnableOption "Whether to enable rustaceanvim.";
+  };
+
+  config = mkIf cfg.enable {
+    programs.nixvim = {
+      plugins.rustaceanvim = {
+        enable = true;
+
+        settings.server = {
+          default_settings.rust-analyzer = {
+            cargo.features = "all";
+            checkOnSave = true;
+            check.command = "clippy";
+            rustc.source = "discover";
+          };
+        };
+      };
+    };
+  };
+}