feat(toggle): add illuminate toggle for which-key (#4708)

## Description
Adds a Toggle-Shortcut to enable/disable
[Illuminate](https://github.com/RRethy/vim-illuminate)

I dont think 'leader ux' is the right shortcut here. I just took the
next free one.


![image](https://github.com/user-attachments/assets/65990e1b-f527-4691-8d2e-eee103695bff)

lua/lazyvim/plugins/extras/editor/illuminate.lua

@@ -15,6 +15,21 @@ return {
     config = function(_, opts)
       require("illuminate").configure(opts)
 
+      Snacks.toggle({
+        name = "Illuminate",
+        get = function()
+          return not require("illuminate.engine").is_paused()
+        end,
+        set = function(enabled)
+          local m = require("illuminate")
+          if enabled then
+            m.resume()
+          else
+            m.pause()
+          end
+        end,
+      }):map("<leader>ux")
+
       local function map(key, dir, buffer)
         vim.keymap.set("n", key, function()
           require("illuminate")["goto_" .. dir .. "_reference"](false)