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/settings/testing.py

@@ -0,0 +1,35 @@
+import os
+
+os.environ.setdefault("LIBRETIME_DEBUG", "true")
+os.environ.setdefault("LIBRETIME_GENERAL_API_KEY", "testing")
+
+# pylint: disable=wrong-import-position,unused-import
+from .prod import (
+    ALLOWED_HOSTS,
+    API_VERSION,
+    AUTH_PASSWORD_VALIDATORS,
+    AUTH_USER_MODEL,
+    CONFIG,
+    DATABASES,
+    DEBUG,
+    DEFAULT_AUTO_FIELD,
+    INSTALLED_APPS,
+    LANGUAGE_CODE,
+    LOGGING,
+    MIDDLEWARE,
+    REST_FRAMEWORK,
+    ROOT_URLCONF,
+    SECRET_KEY,
+    STATIC_URL,
+    TEMPLATES,
+    TIME_ZONE,
+    USE_I18N,
+    USE_L10N,
+    USE_TZ,
+    WSGI_APPLICATION,
+)
+
+# Testing
+# https://docs.djangoproject.com/en/3.2/ref/settings/#test-runner
+
+TEST_RUNNER = "libretime_api.tests.runner.ManagedModelTestRunner"