add arrow plugin

plugins/arrow.nix

@@ -0,0 +1,16 @@
+{ icons, pkgs, ... }:
+{
+  opts.enable = true;
+
+  extra = {
+    packages = [ pkgs.vimPlugins.arrow-nvim ];
+
+    config = ''
+      require('arrow').setup({
+        show_icons = true,
+        leader_key = ';', -- Recommended to be a single key
+        buffer_leader_key = 'm', -- Per Buffer Mappings
+      })
+    '';
+  };
+}