feat(indent-blankline): add which-key toggles (#4122)

## Description

Add which-key toggle mappings for toggling both the indention guides,
and also scope highlight on a per buffer basis.

## Screenshots


![2024-07-20_08-16](https://github.com/user-attachments/assets/7b282868-c035-4f71-97dd-5738cd953713)

## Checklist

- [x] I've read the
[CONTRIBUTING](https://github.com/LazyVim/LazyVim/blob/main/CONTRIBUTING.md)
guidelines.

---------

Co-authored-by: Folke Lemaitre <folke.lemaitre@gmail.com>

lua/lazyvim/plugins/ui.lua

@@ -225,28 +225,40 @@ return {
   {
     "lukas-reineke/indent-blankline.nvim",
     event = "LazyFile",
-    opts = {
-      indent = {
-        char = "│",
-        tab_char = "│",
-      },
-      scope = { show_start = false, show_end = false },
-      exclude = {
-        filetypes = {
-          "help",
-          "alpha",
-          "dashboard",
-          "neo-tree",
-          "Trouble",
-          "trouble",
-          "lazy",
-          "mason",
-          "notify",
-          "toggleterm",
-          "lazyterm",
+    opts = function()
+      LazyVim.toggle.map("<leader>ug", {
+        name = "Indention Guides",
+        get = function()
+          return require("ibl.config").get_config(0).enabled
+        end,
+        set = function(state)
+          require("ibl").setup_buffer(0, { enabled = state })
+        end,
+      })
+
+      return {
+        indent = {
+          char = "│",
+          tab_char = "│",
         },
-      },
-    },
+        scope = { show_start = false, show_end = false },
+        exclude = {
+          filetypes = {
+            "help",
+            "alpha",
+            "dashboard",
+            "neo-tree",
+            "Trouble",
+            "trouble",
+            "lazy",
+            "mason",
+            "notify",
+            "toggleterm",
+            "lazyterm",
+          },
+        },
+      }
+    end,
     main = "ibl",
   },