`Blob::from_headers` doesn't parse version-id

The `Blob::from_headers` function sets `version_id` to `None` without attempting to parse the `x-ms-version-id` header. This makes it impossible to get the current version id when getting blob properties.   

https://github.com/Azure/azure-sdk-for-rust/blob/azure_storage_blobs-0.21.0/sdk/storage_blobs/src/blob/mod.rs#L249