feat: add config modules

backend/src/config/sandbox_config.py

@@ -0,0 +1,10 @@
+from pydantic import BaseModel, Field
+
+
+class SandboxConfig(BaseModel):
+    """Config section for a sandbox"""
+
+    use: str = Field(
+        ...,
+        description="Class path of the sandbox provider(e.g. src.sandbox.local:LocalSandbox)",
+    )