Cleanup casting for SkTDArray

Sometimes I was returning std::byte* which required a
reinterpret_cast<>() instead of a static_cast<>(). Prefer
returning void* instead of std::bytes*.

Change-Id: I183f379607eb207f4b3506fde177fc1b98e4f617
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/587542
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Herb Derby <herb@google.com>
1 file changed