No settings for blob storage encoding

Reading data from blob storage is done using **blob.read()** method.
When the blob is not encoded using **UTF-8** an error is thrown.

In Python, the encoding is set like this: **open(File, encoding='ISO-8859-1', mode='r').read()**
But it is not possible to set the encoding with bindings or extra parameters when using blob storage in azure python functions.

Please add a mechanism to set the encoding of the blobs in blob storage.

Start by reproducing the failure when blob.read() reads a blob encoded outside UTF-8, then compare it with Python's open(File, encoding='ISO-8859-1', mode='r').read() behavior. Trace the Azure Functions blob-storage binding path and determine where an encoding setting could be supplied; done means a binding or extra parameter can select the encoding and non-UTF-8 blobs are read successfully.

Written by the indexing model from the issue text.