Move ErrorTracker to its own repo and file

Note that the SQlite adapter supports version 2 onwards.

lib/music_library/application.ex

@@ -10,6 +10,7 @@ defmodule MusicLibrary.Application do
     children = [
       MusicLibraryWeb.Telemetry,
       MusicLibrary.Repo,
+      MusicLibrary.ErrorRepo,
       {Ecto.Migrator,
        repos: Application.fetch_env!(:music_library, :ecto_repos), skip: skip_migrations?()},
       {DNSCluster, query: Application.get_env(:music_library, :dns_cluster_query) || :ignore},

lib/music_library/error_repo.ex

@@ -0,0 +1,5 @@
+defmodule MusicLibrary.ErrorRepo do
+  use Ecto.Repo,
+    otp_app: :music_library,
+    adapter: Ecto.Adapters.SQLite3
+end