AdaptiveImageServlet should not stream binaries

[joerghoh]

Feature Request

When possible the AdaptiveImageServlet should not stream binaries through the JVM; there are a number of cases where the asset binary is read from the blobstore and then streamed as-is to the requester. IF the Blobstore supports the download of the binary directly (see Direct Binary Access) this feature should be used instead.

As in AEM CS the streaming of binaries through the JVM is an antipattern, we should implement this feature here as well. It will be transparent for endusers, as this feature requests adapts the behaviour of the AdaptiveImageServlet to that behavior used by the AEM CS ootb asset download.

Describe the solution you'd like
Implement the approach described in the above Oak doc.

Are there alternatives?
nope

Documentation

[joerghoh]

Dependency to wcm-io/io.wcm.testing.aem-mock#50 because the AEM Mocks do not provide sufficient support to adapt the existing test cases.