feat(snacks.picker): added <leader>si to search icons (#5460)

## Description

As it reads on the tin can.

## Related Issue(s)

N/A

## Screenshots

![Screenshot 2025-01-23 at 11 49
49](https://github.com/user-attachments/assets/6c4d0e9a-0a8e-4128-9ef1-b7954ece2bc7)

## Checklist

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

lua/lazyvim/plugins/extras/editor/snacks_picker.lua

@@ -88,6 +88,7 @@ return {
       { "<leader>sd", function() Snacks.picker.diagnostics() end, desc = "Diagnostics" },
       { "<leader>sh", function() Snacks.picker.help() end, desc = "Help Pages" },
       { "<leader>sH", function() Snacks.picker.highlights() end, desc = "Highlights" },
+      { "<leader>si", function() Snacks.picker.icons() end, desc = "Icons" },
       { "<leader>sj", function() Snacks.picker.jumps() end, desc = "Jumps" },
       { "<leader>sk", function() Snacks.picker.keymaps() end, desc = "Keymaps" },
       { "<leader>sl", function() Snacks.picker.loclist() end, desc = "Location List" },