TRTOverlay use DataPool

TRTOverlay use DataPool

ping @jchapman , @ssnyder ,@tadej

This algorithm makes a lot of new for small elements moving them around to DataVector

In principle we have some identifiable Containers(we can get them via and index). These Containers have elements. It is these TRT_LoLumRawData elements that we want to have in a DataPool

• This algorithm unlike it SCT and Pixel cousins does not inherit from a the IDC_OverlayBase so a bit easier to try the idea
• The copy operation take a DataPool . The containers are VIEW. We push elements from the Pool to them
• We have 2 of these container from copies
• Then we want to merge elementsfrom them.
• The 3rd container we merge to is also now a View
• What happens is that SwapElement pops elements from the other 2 (elements are owned by the DataPool)
• We merge (if needed) and then push back to the 3rd.
• More or less we should end up with the 3rd container having elements owned by the DataPool.
• We also do not want to delete elements owned by the DataPool

The above you can see in comments in the code. I am not sure I have done all steps 100% correctly. The code should compile by lets see what the CI says