Is it possible to generate an account-level SAS token for blob storage?

### Which service(blob, file, queue) does this issue concern?
Blob

### Which version of the SDK was used? Please provide the output of `pip freeze`.
azure-storage-blob==12.2.0

### What problem was encountered?
I am trying to generate an account level SAS token from a `BlobServiceClient`. I have looked around a bit and cant seem to figure out how I can create a token or if it is even possible. It looks like you could do this with a BlockBlobClient, but that doesnt seem to exist anymore.

### Have you found a mitigation/solution?
I can use Powershell or Azure Portal to generate the token, but would prefer if I can script it.