Clean up the pixel local reconstruction code (#593)

Address the pixel local reconstruction review comments.

General clean up of the pixel local reconstruction code:
  - remove commented out and obsolete code and data members
  - use named constants more consistently
  - update variable names to follow the coding rules and for better consistency
  - use member initializer lists in the constructors
  - allow `if constexpr` in CUDA code
  - use `std::size` instead of hardcoding the array size
  - convert iterator-based loops to range-based loops
  - replace `cout` and `printf` with `LogDebug` or `LogWarning`
  - use put tokens
  - reorganise the auto-generated cfi files and use them more consistently
  - adjust code after rearranging an `#ifdef GPU_DEBUG` block
  - apply code formatting
  - other minor changes

Improve comments:
  - improve comments and remove obsolete ones
  - clarify comments and types regarding `HostProduct`
  - update comments about `GPU_SMALL_EVENTS` being kept for testing purposes
  - add notes about the original cpu code

Reuse some more common code:
  - move common pixel cluster code to `PixelClusterizerBase`
  - extend the `SiPixelCluster` constructor

Rename classes and modules for better consistency:
  - remove the `TrackingRecHit2DCUDA.h` and `gpuClusteringConstants.h` forwarding headers
  - rename `PixelRecHits` to `PixelRecHitGPUKernel`
  - rename SiPixelRecHitFromSOA to SiPixelRecHitFromCUDA
  - rename `siPixelClustersCUDAPreSplitting` to `siPixelClustersPreSplittingCUDA`
  - rename `siPixelRecHitsCUDAPreSplitting` to `siPixelRecHitsPreSplittingCUDA`
  - rename `siPixelRecHitsLegacyPreSplitting` to `siPixelRecHitsPreSplittingLegacy`
  - rename `siPixelRecHitHostSoA` to `siPixelRecHitSoAFromLegacy`

Re-apply changes from cms-sw#29805 that were lost in the Patatrack branch.

RecoPixelVertexing/PixelTrackFitting/plugins/PixelTrackDumpCUDA.cc

@@ -2,7 +2,7 @@
 
 #include "CUDADataFormats/Common/interface/Product.h"
 #include "CUDADataFormats/Track/interface/PixelTrackHeterogeneous.h"
-#include "CUDADataFormats/TrackingRecHit/interface/TrackingRecHit2DCUDA.h"
+#include "CUDADataFormats/TrackingRecHit/interface/TrackingRecHit2DHeterogeneous.h"
 #include "CUDADataFormats/Vertex/interface/ZVertexHeterogeneous.h"
 #include "DataFormats/Common/interface/Handle.h"
 #include "FWCore/Framework/interface/ConsumesCollector.h"