Feature request: dependency inject `*_ltex.json` path function (`ltex_filename()`)

[mawkler]

First of all, thanks for this awesome plugin!

I would like to extend it to put all *_ltex.json files in the same directory, like how :help 'undodir' works by putting all your undo files in $XDG_STATE_HOME/nvim/undo// with the file path separators replaced with %. That way I don't litter my working directories with a bunch of json files whenever I edit a Markdown file.

I think I could achieve this if I could override ltex_filename() from my user configuration, which currently isn't possible. We could therefore add a configuration option like file_settings.path or something similar which is a function:

opts = {
  file_settings = {
    path = function(current_file)
      -- returns path to settings file associated with `current_file`
    end
  }
}

This function would get set to ltex_filename() by default.

What do you say? I could try to create a PR if you agree with this?

[YodaEmbedding]

Fix for lazy.nvim users:

return {
  -- "jhofscheier/ltex-utils.nvim",
  "YodaEmbedding/ltex-utils.nvim",

  branch = "yodaembedding/main",
}