Feature request: Quick Fix for adding function

[TheFirstAvenger]

One feature I miss from a previous life in Eclipse/Java is the ability to quick fix an "is undefined or private" error by adding the function at the end of the correct module. For example, if I am writing code and come across the need to get all users for a particular country, but that doesn't currently exist in the Accounts context, I might write:

assign(socket, :users_in_country, Accounts.get_all_users_for_country(country))

and then ElixirLS would complain that MyApp.Accounts.get_all_users_for_country/1 is undefined or private.

The quick fix would insert the following to the end of the MyApp.Accounts module and jump over to that file:

  def get_all_users_for_country(country) do

  end
end

with the cursor inside the function, ready to implement it.

[lukaszsamson]

A PR would be welcome