Minor Launching an asynchronous conversion on a ManagedBlob does not work as expected.
Anyway, the point of a ManagedBlob is not to be downloaded and then converted if the provider supports the conversion.
Launching an async conversion on the ConversionService should do the following:
- launch the ConversionWork
- the work check if the blob is a ManagedBlob, and if its linked BlobProvider can handle the conversion (through BlobProvider#getAvailableConversions)
- if yes, mark the scheduled conversion as completed and store a boolean managedBlob to true, and other parameters needed to recompute the convert URL
- when polling for the conversion result, if managedBlob is true, returns a resultURL which is the @convert URL accessible through GET.
This does not break the existing flow, and allow us to avoid converting blobs ourselves if the provider supports it.
