### What this PR does / why we need it?
refer to https://github.com/vllm-project/vllm-ascend/issues/6391,
Currently adapted the complete process of event publishing in vllm:
* `kv_connector_model_runner_mixin` invoke kv-connector
`get_kv_connector_kv_cache_events` func to collect kvevents
* in `scheduler.py` , it's `update_from_output` func will invoke
`_update_from_kv_xfer_finished` which invoke
`connector.update_connector_output` to collect kv-events from all
kv-worker, and then scheduler will invoke `connector.take_events` api to
collect all kv-events and add it to the events which from
`kv_cache_manager`
### Does this PR introduce _any_ user-facing change?
no
### How was this patch tested?
You can add `--kv-events-config` parameter to the `vllm server` command
to enable this feature.
- vLLM version: v0.15.0
- vLLM main:
d7e17aaacd
---------
Signed-off-by: yejj710 <abyss1999@163.com>
Co-authored-by: fems14 <1804143737@qq.com>
8b23554741