Fix use of references to DD4hep handles

In DD4hep mode the DeXyz detector types are handles (kind of smart pointers) and they are usually temporary instances, so they should not be kept by reference, but copied otherwise one will get segfaults (like in Detector!368 (comment 6769177)). In DetDesc, instead, one should keep references to the DeXyz instances, that's why I added a helper with LHCb!3596 (merged), which I used here to fix the implementation of a few ToolBinder specializations.

/cc @graven @sponce

added bug fix label

added RTA label

mentioned in merge request Detector!368 (merged)

/ci-test

added ci-test-triggered label

• [2023-05-30 20:15] Validation started with lhcb-master-mr#8072

added hlt2-throughput-decreased label

resolved all threads

approved this merge request

merged

mentioned in commit 266c31d3