[FEATURE REQ] Storage: Should be parse methods for SAS token permissions strings

[Shiney]

Library name

Azure.Storage.Blobs

Please describe the feature.

It would be nice if there was a mechanism of transforming the permissions strings in SAS tokens e.g. "rawcd" into the flags enum for their permissions.

In fact this feature exists in other azure SDKs for example this one in javascript https://github.com/Azure/azure-sdk-for-js/blob/main/sdk/storage/storage-blob/src/sas/BlobSASPermissions.ts

[github-actions]

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @amnguye @jalauzon-msft @jaschrep-msft @nickliu-msft @seanmcc-msft.