feat: introduce TGeoDetectorElementSplitter & splitted detector element constructors

[asalzburger]

This PR introduces a new interface in the TGeo plugin that allows splitting of TGeoDetectorElement objects and adds a necessary constructor for this to the TGeoDetectorElement.

This will be needed for the ALICE o2 studies (generic splitter from disk to trapezoids), but also for the TGeo version of the ATLAS ITk, where dedicated splitters need to be written.

Tagging some interested parties: @paulgessinger @niermann999 @noemina

The splitting has to be activated with a switch:

--geo-tgeo-cyl-disc-split

And then, consequently, all volumes need to define how they wanna perform the splitting, e.g. for no splitting:

--geo-tgeo-cyl-nz-segs -1
--geo-tgeo-cyl-nphi-segs -1
--geo-tgeo-disc-nr-segs -1
--geo-tgeo-disc-nphi-segs -1

versus splitting:

--geo-tgeo-cyl-nz-segs 6
--geo-tgeo-cyl-nphi-segs 32
--geo-tgeo-disc-nr-segs 6
--geo-tgeo-disc-nphi-segs 32

[codecov]

Codecov Report

Merging #873 (8fee3f1) into main (6e94ec0) will not change coverage.
The diff coverage is n/a.

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  Coverage   48.66%   48.66%           
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  Files         331      331           
  Lines       17129    17129           
  Branches     8094     8094           
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  Hits         8336     8336           
  Misses       3087     3087           
  Partials     5706     5706           

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[asalzburger]

Splitting for DiscSurface layers is done:

This is an example of 6 radial splits and 32 phi segments.

[asalzburger]

Splitting for Cylinders enabled.