Update List Blobs API to match the existing documentation

In this [List Blobs API](https://learn.microsoft.com/en-us/rest/api/storageservices/list-blobs?tabs=azure-ad) doc page, it says

"For version 2020-06-12 and later, for accounts with a hierarchical namespace enabled, List Blobs with a delimiter returns the Properties element in the BlobPrefix element. This corresponds with the properties on the directory."

However, this is not reflected in the corresponding [API spec](https://github.com/Azure/azure-rest-api-specs/blob/d0d161eb19d5efd1c3d23d47a5491a53f41cbd7c/specification/storage/data-plane/Microsoft.BlobStorage/preview/2021-12-02/blob.json#LL10048C1-L10048C1). This is blocking the SDK team from adding code to parse those properties and add to the SDK interfaces.

Start with specification/storage/data-plane/Microsoft.BlobStorage/preview/2021-12-02/blob.json at the BlobPrefix definition around line 10048, and compare it with the linked List Blobs documentation. Update the API specification so hierarchical-namespace accounts using a delimiter represent the directory properties in BlobPrefix, then validate that the spec matches the documented response.

Written by the indexing model from the issue text.