[Feat] A Connector that supports Mooncake store (#2913)

### What this PR does / why we need it?
Added a new connector for Mooncake store integration to enable kvcache
reuse in scenarios with system prompts or multi-turn dialogues.

### How was this patch tested?


- vLLM version: v0.10.2
- vLLM main:
5963b98b46

---------

Signed-off-by: LCAIZJ <leichao139636@163.com>
Signed-off-by: fems14 <1804143737@qq.com>
Co-authored-by: fems14 <1804143737@qq.com>
Co-authored-by: Dreamerleader <2270923832@qq.com>
Co-authored-by: Pz1116 <zpbzpb123123@gmail.com>
Co-authored-by: lizy124 <1950471827@qq.com>
Co-authored-by: zouyida2052 <zouyida2002@gmail.com>

vllm_ascend/worker/model_runner_v1.py

@@ -1811,13 +1811,9 @@ class NPUModelRunner(LoRAModelRunnerMixin):
             if self.drafter and self.drafter.name == SpecDcodeType.EAGLE3:
                 hidden_states, aux_hidden_states = hidden_states
 
-        kv_connector_output = None
-        if finished_sending is not None or finished_recving is not None:
-            kv_connector_output = KVConnectorOutput(
-                finished_sending=finished_sending,
-                finished_recving=finished_recving)
-        else:
-            kv_connector_output = None
+        kv_connector_output = KVConnectorOutput(
+            finished_sending=finished_sending,
+            finished_recving=finished_recving)
         finished_sending = None
         finished_recving = None
         with ProfileExecuteDuration().capture_async("post process"):
@@ -2067,8 +2063,6 @@ class NPUModelRunner(LoRAModelRunnerMixin):
             # For the case of no forward caused by receiving remote kv,
             # one round of dummy inference is necessary
             # to prevent hang over the collective calls.
-        if not finished_sending and not finished_recving:
-            return EMPTY_MODEL_RUNNER_OUTPUT
 
         output = copy.copy(EMPTY_MODEL_RUNNER_OUTPUT)
         output.kv_connector_output = KVConnectorOutput(