Move composites test to DaVinciExamples

The following discussion from !711 (merged) should be addressed:

• @sstahl started a discussion: (+3 comments)

  Thanks for this MR. Do you have plans to include some of the changes in !700 (merged) also here?

https://gitlab.cern.ch/lhcb/DaVinci/-/blob/master/DaVinciTests/tests/options/option_davinci_v2_composites.py is presently the only test building particles. It should be moved to DaVinciExamples once !700 (merged) is merged.

added DPA-WP3 testing labels

assigned to @pkoppenb

changed title from Move cmposites test to DaVinciExamples to Move composites test to DaVinciExamples

added Tutorials label

mentioned in merge request !773 (merged)

mentioned in commit 353988ff

closed with merge request !773 (merged)