Add alias creation endpoint

priv/repo/migrations/20210730122017_create_aliases_table.exs

@@ -0,0 +1,12 @@
+defmodule MatrixServer.Repo.Migrations.CreateAliasesTable do
+  use Ecto.Migration
+
+  def change do
+    create table(:aliases, primary_key: false) do
+      add :alias, :string, primary_key: true, null: false
+      add :room_id, references(:rooms, type: :string, on_delete: :delete_all), null: false
+    end
+
+    create index(:aliases, [:room_id])
+  end
+end