[FR] Firebase Storage Emulator Support

As per https://firebase.google.com/docs/emulator-suite/install_and_configure#admin_sdk_availability the current version of the Firebase Admin SDK for Java does not yet provide support for Firebase Storage Emulator.

Indeed, even after setting `FIREBASE_STORAGE_EMULATOR_HOST` in my environment as per https://firebase.google.com/docs/emulator-suite/connect_storage#admin_sdks, that endpoint is simply ignored and requests are still sent to the usual remote URL(https://storage.googleapis.com/storage/v1...)

Is there a rough time horizon, in which this feature will be implemented?

從 issue 中的 Firebase 文件連結開始，尤其是「Admin SDK availability」和「Storage Emulator connection」部分，然後追蹤 Java Admin SDK 如何選擇 Storage 要求端點。報告中沒有提到 repository 檔案或測試；完成標準是 FIREBASE_STORAGE_EMULATOR_HOST 將 Storage 要求路由到 emulator，而不是 storage.googleapis.com，並為該行為提供測試涵蓋。

由索引模型根據 Issue 內容生成。