bug#62536: 30.0.50; Can we add """ ... """ electric pair in elixir, just like python

[Wilhelm Kirschbaum <wkirschbaum@gmail.com>]

>> From: 牟 桐 <mou.tong@outlook.com>
>> Date: Thu, 30 Mar 2023 04:25:07 +0000
>> 
>> In elixir, the docs in src are like this:
>> 
>> ``` elixir-ts-mode
>> defmodule Foo do
>>   @moduledoc """
>>   Foo-related functions.
>> 
>>   ## Examples
>> 
>>       iex> Foo.sum(1, 2)
>>       3
>>   """
>> 
>>   @doc """
>>   Calculate the sum of two numbers.
>>   """
>>   def sum(a, b), do: a + b
>> end
>> ```
>> 
>> In python-mode, input the continious triple quotes, it will 
>> insert the
>> left quotes when electric-pair-mode is on.
>> 
>> python-mode did it here:
>> 
>> https://github.com/emacs-mirror/emacs/blob/bfa3500c3c6e4df58978e84753718cd5358c06fb/lisp/progmodes/python.el#L6599-L6607
>> 
>> 
>> https://github.com/emacs-mirror/emacs/blob/bfa3500c3c6e4df58978e84753718cd5358c06fb/lisp/progmodes/python.el#L6637-L6639
>> 
>> 
>> This behavior is also very common in elixir, so can we add this 
>> to
>> elixir-ts-mode? thx
>
> Wilhelm, WDYT?

Yes, I think we should add some version of this.  I am currently 
testing a
syntax-propertize-function addition to solve an issue related to
electric-pair-mode and will have a look at this straight after.

There was another request to automatically insert `end` when `do` 
is
entered, which might be a good addition as well.