Refactor Core things, including Ecto handling, ActivityPub & Transmogrifier modules

* Data doesn't need anymore to be converted to ActivityStream format to
be saved (this was taken from Pleroma and not at all a good idea here)
* Everything saved when creating an event is inserted into PostgreSQL in
a single transaction

lib/mix/tasks/mobilizon/setup_search.ex

@@ -0,0 +1,49 @@
+defmodule Mix.Tasks.Mobilizon.SetupSearch do
+  @moduledoc """
+  Temporary task to insert search data from existing events
+
+  This task will be removed in version 1.0.0-beta.3
+  """
+
+  use Mix.Task
+
+  alias Mobilizon.Service.Search
+  alias Mobilizon.Storage.Repo
+  alias Mobilizon.Events.Event
+  import Ecto.Query
+
+  require Logger
+
+  @shortdoc "Insert search data"
+  def run([]) do
+    Mix.Task.run("app.start")
+
+    events =
+      Event
+      |> preload([e], :tags)
+      |> Repo.all()
+
+    nb_events = length(events)
+
+    IO.puts("\nStarting setting up search for #{nb_events} events, this can take a while…\n")
+    insert_search_event(events, nb_events)
+  end
+
+  defp insert_search_event([%Event{url: url} = event | events], nb_events) do
+    case Search.insert_search_event(event) do
+      {:ok, _} ->
+        Logger.debug("Added event #{url} to the search")
+
+      {:error, res} ->
+        Logger.error("Error while adding event #{url} to the search: #{inspect(res)}")
+    end
+
+    ProgressBar.render(nb_events - length(events), nb_events)
+
+    insert_search_event(events, nb_events)
+  end
+
+  defp insert_search_event([], nb_events) do
+    IO.puts("\nFinished setting up search for #{nb_events} events!\n")
+  end
+end