Make get() return entire session instead of SessionUpdate of the last filter

[jesper-friis]

Assume that you have the following pipeline

pipe = resource >> mapping

Now, when you are calling pipe.get() you will get the SessionUpdate from mapping. However, you would normally be interested in the content (e.g. collection_id) placed in the session by resource. But that is not available from pipe.

Hence, update otelib such that the fetch() method returns the entire session rather than the updates by the last filter.

[CasperWA]

This needs to be addressed and discussed in more detail. What is the expected return content from pipeline.get()? What is the expected way of using OTELib?