Complete streaming support for Browsers

The Encryption SDK should support streaming for large files.

The message is already framed,
so the fact that AES-GCM operations in WebCrypto are one-shot is not an issue.
This is actually a benefit since a partial decrypt of AES-GCM
without verifying the MAC is a security issue.
However, all the WebCrypto APIs are one-shot.
Streaming the signature or digest functions is not supported.

This issue is to track all streaming support,
and sub issues can be opened to address specific parts
or point solutions.