fix: util regex highlighter producing error when scrolling too fast

[kalkafox]

Description

When scrolling through files or typing continuously on a search window, the regex highlighter has a chance to produce this error:

The affected function is rewritten by wrapping nvim_buf_set_option in a protected call, and returning whether that call succeeded as a boolean value.

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Open a new [S]earch [F]iles window, and type or scroll.

Configuration:

• Neovim version (nvim --version):

NVIM v0.8.2
Build type: RelWithDebInfo
LuaJIT 2.1.0-beta3
Compiled by runneradmin@fv-az28-353

Features: -acl +iconv +tui
See ":help feature-compile"

   system vimrc file: "$VIM\sysinit.vim"
  fall-back for $VIM: "C:/Program Files (x86)/nvim/share/nvim"

Run :checkhealth for more info

• Operating system and version: Windows 10 Pro 21H2

Checklist:

• My code follows the style guidelines of this project (stylua)
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (lua annotations)

[Conni2461]

Thanks :)