Incorporate async-compatible, process-subset-compatible barrier function. With this API, barrier names must be completely unique, and many places must be adjusted to take this into account. There is also an issue with inconsistency between `jax.process_index()` and `distributed.client.process_id`, which is resolved by `initialize_runtime_to_distributed_ids`. This function will be removed as soon as the discrepancy is resolved.

[copybara-service[bot]]

Incorporate async-compatible, process-subset-compatible barrier function. With this API, barrier names must be completely unique, and many places must be adjusted to take this into account. There is also an issue with inconsistency between jax.process_index() and distributed.client.process_id, which is resolved by initialize_runtime_to_distributed_ids. This function will be removed as soon as the discrepancy is resolved.