Provide C implementation for asyncio.current_task

Feature or enhancement

By providing a C implementation for asyncio.current_task, its performance can be improved.

Pitch

Performance improvement.

From Instagram profiling data, we've found that this function is called frequently, and a C implementation (in Cinder 3.8) showed more than 4x speedup in a microbenchmark.

Previous discussion

N/A

Linked PRs