Support extra user dictionaries

[legeana]

Hi,
Would the project be open to supporting additional user dictionaries?

Instead of

lspconfig.harper_ls.setup {
  settings = {
    ["harper-ls"] = {
      userDictPath = "~/dict.txt",
      fileDictPath = "~/.harper/",
    }
  },
}

I would like to be able to do this:

lspconfig.harper_ls.setup {
  settings = {
    ["harper-ls"] = {
      userDictPath = "~/dict.txt",
      extraUserDictPaths = { "~/extra-dict-1.txt", "~/extra-dict-2.txt" },
      fileDictPath = "~/.harper/",
    }
  },
}

This would load extra words into the global dictionary on startup and still allow the user to update their primary userDictPath with code actions as before. There will be no editing support for extraUserDictPaths within harper.

The reason I would like to have this is to allow

• Autogenerated dictionaries such as lists of usernames automatically added to a dictionary via cron. I would prefer to avoid adding them manually into my user dictionary to avoid unnecessary bloating, but having them in the global dictionary prevents false positives.
• Having a separate primary user dictionary for work while still loading my personal dictionary for spellcheck. This would prevent me from accidentally adding work-related words to my personal dictionary.

I will be happy to work on implementing this, please let me know if you are open to accepting this contribution.