FileVersionProvider/GenerateCacheKey uses synchronous stream access

[slaneyrw]

The FileVersionProvider used by the Asset.GenerateCacheKey uses synchronous access to the fileinfo stream ( passes stream directly to the SHA algorithm ), where as the AssetBuilder uses CopyToAsync.

Can you please ensure only Async stream access methods are used, our source is NOT a local file and requires an asynchronous read from an external source.

There is no "hook" that allows the source to be read asynchonously before the cachekey is calculated for the first time.

[slaneyrw]

This also manifests itself in the tag helpers. They need to use the ProcessAsync override, not the Process override.