feat: export simulation geometry to CAD models (STEP)

[wdconinc]

Briefly, what does this PR introduce?

This PR exports the geometry to STEP files for CAD import and dimensioning. There are no real settings to tweak, but to increase the level at which volumes are exported, hints can be added to the yaml file. Detectors can also be removed (currently only the ACTS subassemblies are removed since they don't do anything).

There are 'issues' that need to be addressed, but they have to be addressed in npsim:

• units are off (npdet_to_step use the cm value from TGeo and writes them as inch values in STEP) npdet_to_step exports to incorrect units (mm/cm) npsim#20,
• some shapes cannot be exported; not sure yet which ones and it makes more sense to bypass them in npsim npdet_to_step cannot handle TGeoTessellation npsim#21.

What kind of change does this PR introduce?

• Bug fix (issue #__)
• New feature (issue #__)
• Documentation update
• Other: __

Please check if this PR fulfills the following:

• Tests for the changes have been added
• Documentation has been added / updated
• Changes have been communicated to collaborators

Does this PR introduce breaking changes? What changes might users need to make to their code?

No.

Does this PR change default behavior?

No.

[wdconinc]

This now works "well enough" for merging: imported y-up and created a back view with left view section drawing.

(source: https://cad.onshape.com/documents/9fb38cc05081c441e152b5e1/w/441fcb286b98a55b7de89480/e/fe210e22e03730344768d9d6?renderMode=0&uiState=65f905d605a2a05c1bde1005, which is import of artifact at https://github.com/eic/epic/actions/runs/8336052681)

As I wrote, caveats:

• cm/mm confusion: the STEP file needs scaling by factor 10,
• barrel hcal is bypassed due lack of support for TGeoTessellated,
• too complicated for freecad? fails to load...
• requires "fast" geometry, don't attempt on local full geometry with fibers and all.

[wdconinc]

Now with the tracking detectors (except not yet MPGDOuterBarrel), and as a sliced section view:

[wdconinc]

Now with MPGD properly resolved:

[wdconinc]

This now exports also things like epic_drich_only.stp, but the drawback is that you don't get good info on where the interaction point is in these CAD models. This imports in FreeCAD for those who prefer that for CAD (I can't see how FreeCAD can be told to import models with Y as pointing up, instead of having Z as pointing up, so my rotations are off).