Handle Apollo multipart failed-request inspection safely

## Context

The Apollo 4 and Apollo 5 integrations inspect HTTP response bodies to detect GraphQL `errors`. Multipart and incremental responses need separate handling so inspection does not buffer, block, or consume streaming bodies.

## Scope

- Define safe failed-request inspection for multipart/incremental responses in `sentry-apollo-4` and `sentry-apollo-5`.
- Preserve spans and breadcrumbs when body inspection is skipped or unsupported.
- Decide between skipping failed-request body inspection for multipart responses and parsing multipart parts for GraphQL errors.
- Add tests covering streaming behavior and body preservation.

WebSocket subscription instrumentation remains out of scope.

先閱讀 sentry-apollo-4 和 sentry-apollo-5 的整合程式碼，追蹤對 multipart 和增量回應的失敗請求 body 檢查。新增串流行為和 body 保留的測試，包括略過檢查或不支援檢查的情況。完成的條件是，multipart 處理不會緩衝、阻塞或消耗 body，同時 spans 和 breadcrumbs 仍獲得保留。

由索引模型根據 Issue 內容生成。