Add diagnostics plugin and icons to Neovim configuration

hosts/totsugeki/home-manager/development/nixvim/trouble.nix

@@ -0,0 +1,25 @@
+{ ... }: {
+  programs.nixvim = {
+    plugins.trouble = {
+      enable = true;
+      settings = {
+        auto_refresh = true;
+        focus = true;
+        follow = false;
+        keys = {
+          "<cr>" = "jump_close";
+          "s" = "jump_vsplit";
+          "S" = "jump_split";
+        };
+        win = {
+          type = "float";
+          border = "rounded";
+        };
+      };
+    };
+    keymaps = [{
+      action = "<cmd>Trouble diagnostics toggle<cr>";
+      key = "<leader>dg";
+    }];
+  };
+}