Add config.large_file_cutoff_kilobytes to handle large single line files

[Avi-D-coder]

I have defaulted it to 50kb, not sure what the right number is, probably much lower. I encounter this error when opening a large single line json file.

It would be nice to catch this error and disable illuminate on the buffer automatically, but I don't have time to write that right now.

Error detected while processing CursorMoved Autocommands for "*":                                                                                                                               
Error executing lua callback: Vim:E363: Pattern uses more memory than 'maxmempattern'                                                                                                           
stack traceback:                                                                                                                                                                                
        [C]: in function 'synID'                                                                                                                                                                
        ...m/lazy/vim-illuminate/lua/illuminate/providers/regex.lua:60: in function 'is_ready'                                                                                                  
        ...share/nvim/lazy/vim-illuminate/lua/illuminate/engine.lua:178: in function 'get_provider'                                                                                             
        ...share/nvim/lazy/vim-illuminate/lua/illuminate/engine.lua:111: in function 'refresh_references'                                                                                       
        ...share/nvim/lazy/vim-illuminate/lua/illuminate/engine.lua:50: in function <...share/nvim/lazy/vim-illuminate/lua/illuminate/engine.lua:49>