[WIP] Acts Geo Gen3 DD4hep conversion

[tmadlener]

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• Needs feat: Gen3 DD4hep construction acts-project/acts#5193
• Includes Fix several deprecation warnings from Acts #45

This is a work in progress with the main purpose of being able to share ongoing efforts. So far the efforts focus on getting (parts) of the MAIA_v0 geometry conversion tested and evaluated against upstream work happening at currently living on https://github.com/paulgessinger/acts/tree/feat/dd4hep-gen3

For the MAIA_v0 geometry, this needs key4hep/k4geo#549

[paulgessinger]

Do you think something like this should exist at the library level?

[tmadlener]

I am not entirely sure. I don't see a way to make this general enough to be useful without inventing another semi DSL just for this purpose. This specific thing works for our case, where there is one (or a few) endcap layers that protrude into the cylinder formed by the outermost barrel layer(s). However, we currently only have this nesting once (in a subdetector). As soon as we have, e.g. two different levels of protrusion it no longer works. The way out would be to simply call this thing twice with different configurations, but then one would have to potentially add more config, e.g. to allow for "empty" layers.

Given that it's fairly straight forward to build this on our end on top of the proposed API, I would keep it in "userland" and see if it's common enough there to merit upstreaming later.

[tmadlener]

With the changes in paulgessinger/acts#33 we now also support planar geometries, like LUXE