Better handling for streamed lobs

When the ws translator returns a streamed result internal operations, such as adding to a tuple buffer may attempt to obtain the length, etc. that render the lob unusable and result in opaque errors, such as

"TEIID30035 Wrong type of data found or no data found; expecting streamable object from the buffer manager"

We should make streaming best effort (such as resorting to the copy on read logic), more fool-proof with internal operations, or at least improve the error message.