Added a new backend settings system

This can be used for saving runtime-configurable settings in the database.

tests_integration/tests/setting/test_get.py

@@ -0,0 +1,44 @@
+"""Integration tests for the Vendor API endpoint."""
+
+import httpx
+
+URL = "http://spoolman:8000"
+
+
+def test_get_currency():
+    """Test getting the currency setting."""
+    # Execute
+    result = httpx.get(f"{URL}/api/v1/setting/currency")
+    result.raise_for_status()
+
+    # Verify
+    setting = result.json()
+    assert setting == {
+        "value": '"EUR"',
+        "is_set": False,
+        "type": "string",
+    }
+
+
+def test_get_unknown():
+    """Test getting an unknown setting."""
+    # Execute
+    result = httpx.get(f"{URL}/api/v1/setting/unknown")
+    assert result.status_code == 404
+
+
+def test_get_all():
+    """Test getting all settings."""
+    # Execute
+    result = httpx.get(f"{URL}/api/v1/setting/")
+    result.raise_for_status()
+
+    # Verify
+    settings = result.json()
+    assert settings == {
+        "currency": {
+            "value": '"EUR"',
+            "is_set": False,
+            "type": "string",
+        },
+    }