feat(api): split api into multiple apps (#1626)

Fixes #1622

- split the api into 4 apps: core, history, schedule, storage
- exploded the settings into testing/prod

api/libretime_api/storage/serializers/file.py

@@ -0,0 +1,11 @@
+from rest_framework import serializers
+
+from ..models import File
+
+
+class FileSerializer(serializers.HyperlinkedModelSerializer):
+    id = serializers.IntegerField(read_only=True)
+
+    class Meta:
+        model = File
+        fields = "__all__"