Long running operations Support

In Azure SDK/API as an example,
Long running operations are performed in the following flow?

1. A URL is returned that can be used to retrieve the result of the operation once completed.
2. The URL can be used to monitor the status of the operation, at regular intervals until it is completed.
3. Optionally a callback URL is availed that can be used to get notification once a long running operation is completed.

Technically, this looks like polling and a callback URL.

Do we have a spec on this for Graph SDKs @baywet @andrueastman @darrelmiller @ddyett @Ndiritu @samwelkanda

先檢閱 issue 中的 Azure SDK/API 範例和 Graph SDK 參考，以確認是否已有關於長時間執行作業、輪詢和回呼 URL 的規格。完成此項需要一份已達成共識的 Graph SDK 規格或範圍明確的實作要求；payload 未指明任何檔案或測試。