add gitsigns, add nvim-web-devicons, update lualine and neo-tree

config/plugins/git/gitsigns.nix

@@ -0,0 +1,27 @@
+_: {
+  plugins.gitsigns = {
+    enable = true;
+    settings = {
+      signs = {
+        add = {
+          text = "▎";
+        };
+        change = {
+          text = "▎";
+        };
+        delete = {
+          text = "";
+        };
+        topdelete = {
+          text = "";
+        };
+        changedelete = {
+          text = "▎";
+        };
+        untracked = {
+          text = "▎";
+        };
+      };
+    };
+  };
+}