FCCee LAr ECAL geometry update

[BrieucF]

• Higher granularity for the FCC-ee LAr ECAL (12 layers instead of 8)
• Updated geometry to reflect the most up to date version of the detector design (LAr gap size, absorbed size, inner radius, number of plates, ...)
• Introduction of the detector segmentation based on constant theta steps instead of constant eta steps

NB: the theta segmentation is not yet used in the default geometry because some reconstruction tools (e.g. CaloTowerTool) rely on the eta segmentation, those will have to be updated first.

The validation is based on the following tools: FCCAnalyses calo n-tuple maker and performance plot maker.

Basic cell/cluster distributions:

Performance plots for the updated geometry (no upstream material correction applied --> energy resolution not centered around 0):

Performance for the previous geometry (no upstream material correction applied --> energy resolution not centered around 0):

[vvolkl]

Superseded by HEP-FCC/FCCDetectors#1 and HEP-FCC/k4RecCalorimeter#3