add lazy git plugin

probably will configure it as well, this app looks kinda cool

lua/custom/plugins/lazygit.lua

@@ -0,0 +1,7 @@
+return {
+  "kdheepak/lazygit.nvim",
+  -- optional for floating window border decoration
+  dependencies = {
+    "nvim-lua/plenary.nvim",
+  },
+}