feat(driver): reduce eventfd IO

[Berrysoft]

Each call to Waker::wake writes to the eventfd, which is too annoying. This PR provides a faster path. When the waker is on the same thread, no need to write to the eventfd.

The enable_poll switch of proactor builder provides compatibility to custom event loops, which may poll the io-uring fd in other frameworks. When the switch is enabled, the fast path is disabled.

[Berrysoft]

Thanks to @oxalica, this PR also address two small fixes:

• min_timeout gets current time even when no timeout in the queue.
• Add a local queue to the runtime to reduce sync cost of SegQueue

[George-Miao]

LGTM