Rename webgpu_cpp.h to api_cpp.h and webgpu_cpp_print.h to api_cpp_print.h.
BUG=dawn:1201
Change-Id: Icceee0fd70fb6497a9e2b0891b5c5843787593f9
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/71720
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Junwei Fu <junwei.fu@intel.com>