[VecGeom-175] Bug fixes to polycone
Details:
- Implemented a new GenericKernelForContainsAndInside()
- Use the new kernel for Contains() and Inside()
- Temporary: introduced an assert() to compare old and new implementations of Contains() and new Contains().
- Add handling for special cases in the above kernel -- e.g. points on axis and on the surface between two sections
- Reset fNz at end of construction
- Introduce the test case described in VecGeom-175 into the polycone unit test
- Some cleanup
- Remove unnecessary member data fEndPhi
- a few white space fixes cf. coding conventions