C++ code should not throw its own exceptions

[scotts]

🐛 Describe the bug

Currently, the C++ VideoDecoder code will throw normal C++ exceptions such as throw std::runtime_exception(). This has caused some problems with how PyTorch handles custom C++ ops, resulting in segfaults. We should exclusively use PyTorch macros (TORCH_CHECK(), C10_THROW_ERROR(), etc) to make sure our C++ error handling correctly propagates to Python.

Versions

All versions.