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/config/autocmds.lua

@@ -55,20 +55,22 @@ vim.api.nvim_create_autocmd("FileType", {
   group = augroup("close_with_q"),
   pattern = {
     "PlenaryTestPopup",
+    "checkhealth",
+    "dbout",
+    "gitsigns-blame",
     "grug-far",
     "help",
     "lspinfo",
+    "neotest-output",
+    "neotest-output-panel",
+    "neotest-summary",
     "notify",
     "qf",
+    "snacks_win",
+    "snacks_notif",
     "spectre_panel",
     "startuptime",
     "tsplayground",
-    "neotest-output",
-    "checkhealth",
-    "neotest-summary",
-    "neotest-output-panel",
-    "dbout",
-    "gitsigns-blame",
   },
   callback = function(event)
     vim.bo[event.buf].buflisted = false
@@ -124,29 +126,3 @@ vim.api.nvim_create_autocmd({ "BufWritePre" }, {
     vim.fn.mkdir(vim.fn.fnamemodify(file, ":p:h"), "p")
   end,
 })
-
-vim.filetype.add({
-  pattern = {
-    [".*"] = {
-      function(path, buf)
-        return vim.bo[buf]
-            and vim.bo[buf].filetype ~= "bigfile"
-            and path
-            and vim.fn.getfsize(path) > vim.g.bigfile_size
-            and "bigfile"
-          or nil
-      end,
-    },
-  },
-})
-
-vim.api.nvim_create_autocmd({ "FileType" }, {
-  group = augroup("bigfile"),
-  pattern = "bigfile",
-  callback = function(ev)
-    vim.b.minianimate_disable = true
-    vim.schedule(function()
-      vim.bo[ev.buf].syntax = vim.filetype.match({ buf = ev.buf }) or ""
-    end)
-  end,
-})