Introduce the group activity section

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

priv/repo/migrations/20210215092515_add_activity_table.exs

@@ -0,0 +1,20 @@
+defmodule Mobilizon.Storage.Repo.Migrations.AddActivityTable do
+  use Ecto.Migration
+
+  def change do
+    create table(:activities) do
+      add(:priority, :integer, null: false)
+      add(:type, :string, null: false)
+      add(:author_id, references(:actors, on_delete: :delete_all), null: false)
+      add(:group_id, references(:actors, on_delete: :delete_all), null: false)
+      add(:subject, :string, null: false)
+      add(:subject_params, :map, null: false)
+      add(:message, :string)
+      add(:message_params, :map)
+      add(:object_type, :string)
+      add(:object_id, :string)
+
+      timestamps(updated_at: false, type: :utc_datetime)
+    end
+  end
+end