feat(core)!: move a bunch of LazyVim features to snacks.nvim (#4706)

## Description

LazyVim comes with a bunch of smaller QoL plugin like features, but it's
not easy for non LazyVim users to use them.

That's why I started working on
[snacks.nvim](https://github.com/folke/snacks.nvim), a collection of
small QoL plugins for Neovim.

Snacks also includes a bunch of new improvements to these features.

This PR fully integrates with snacks.

## Todo

- [ ] add proper deprecations where needed
- [ ] create snacks docs
- [ ] document all the new improvements relevant to LazyVim users

## Closes

- [ ] #4492 
- [ ] #4333
- [ ] #4687

## Screenshots

<!-- Add screenshots of the changes if applicable. -->

## Checklist

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

lua/lazyvim/plugins/ui.lua

@@ -1,39 +1,4 @@
 return {
-  -- Better `vim.notify()`
-  {
-    "rcarriga/nvim-notify",
-    keys = {
-      {
-        "<leader>un",
-        function()
-          require("notify").dismiss({ silent = true, pending = true })
-        end,
-        desc = "Dismiss All Notifications",
-      },
-    },
-    opts = {
-      stages = "static",
-      timeout = 3000,
-      max_height = function()
-        return math.floor(vim.o.lines * 0.75)
-      end,
-      max_width = function()
-        return math.floor(vim.o.columns * 0.75)
-      end,
-      on_open = function(win)
-        vim.api.nvim_win_set_config(win, { zindex = 100 })
-      end,
-    },
-    init = function()
-      -- when noice is not enabled, install notify on VeryLazy
-      if not LazyVim.has("noice.nvim") then
-        LazyVim.on_very_lazy(function()
-          vim.notify = require("notify")
-        end)
-      end
-    end,
-  },
-
   -- This is what powers LazyVim's fancy-looking
   -- tabs, which include filetype icons and close buttons.
   {
@@ -55,9 +20,9 @@ return {
     opts = {
       options = {
         -- stylua: ignore
-        close_command = function(n) LazyVim.ui.bufremove(n) end,
+        close_command = function(n) Snacks.bufdelete(n) end,
         -- stylua: ignore
-        right_mouse_command = function(n) LazyVim.ui.bufremove(n) end,
+        right_mouse_command = function(n) Snacks.bufdelete(n) end,
         diagnostics = "nvim_lsp",
         always_show_bufferline = false,
         diagnostics_indicator = function(_, _, diag)
@@ -226,7 +191,7 @@ return {
     "lukas-reineke/indent-blankline.nvim",
     event = "LazyFile",
     opts = function()
-      LazyVim.toggle.map("<leader>ug", {
+      Snacks.toggle({
         name = "Indention Guides",
         get = function()
           return require("ibl.config").get_config(0).enabled
@@ -234,7 +199,7 @@ return {
         set = function(state)
           require("ibl").setup_buffer(0, { enabled = state })
         end,
-      })
+      }):map("<leader>ug")
 
       return {
         indent = {
@@ -244,17 +209,19 @@ return {
         scope = { show_start = false, show_end = false },
         exclude = {
           filetypes = {
-            "help",
+            "Trouble",
             "alpha",
             "dashboard",
-            "neo-tree",
-            "Trouble",
-            "trouble",
+            "help",
             "lazy",
             "mason",
+            "neo-tree",
             "notify",
+            "snacks_notif",
+            "snacks_terminal",
+            "snacks_win",
             "toggleterm",
-            "lazyterm",
+            "trouble",
           },
         },
       }