feat: execute service as distributed erlang (#96)

To create a cluster with distributed nodes, the following changes were made:

* Use [`dns_cluster`][0] to execute distributed nodes
* Add _script_ to execute distributed nodes locally

Also, improve local execution by:

* Use [`mix release`][1] to make easier [deploy `phoenix`][2]
* Use [`compose watch`][3] to synchronize code from the host with the service

Some minor improvements:

* Ignore files and folders in git and docker
* Remove boilerplate comments

[0]: https://github.com/phoenixframework/dns_cluster
[1]: https://hexdocs.pm/mix/Mix.Tasks.Release.html
[2]: https://hexdocs.pm/phoenix/releases.html
[3]: https://docs.docker.com/compose/how-tos/file-watch/

Co-authored-by: Joao P Dubas <joao.dubas@gmail.com>
Reviewed-on: #96
Co-authored-by: Joao P Dubas <joao.dubas+gitea@gmail.com>
Co-committed-by: Joao P Dubas <joao.dubas+gitea@gmail.com>

mix.exs

@@ -36,6 +36,7 @@ defmodule Wabanex.MixProject do
       {:credo, "~> 1.7.0", only: [:dev, :test], runtime: false},
       {:crudry, "~> 2.4.0"},
       {:dialyxir, "~> 1.4.0", only: [:dev, :test], runtime: false},
+      {:dns_cluster, "~> 0.1.1"},
       {:ecto_sql, "~> 3.12.0"},
       {:gettext, "~> 0.25.0"},
       {:jason, "~> 1.4.0"},