implement model runner v2 basic framework (#5051)

### What this PR does / why we need it?
This PR aim to implement model runner v2 basic framework in vllm-ascend,
the e2e function is not guaranteed by this pr.
 
### Does this PR introduce _any_ user-facing change?
use envs.VLLM_USE_V2_MODEL_RUNNER to decide if choose model_runenr_v2.

### How was this patch tested?

- vLLM version: v0.12.0
- vLLM main:
ad32e3e19c

---------

Signed-off-by: Ronald1995 <ronaldautomobile@163.com>

docs/source/developer_guide/contribution/testing.md

@@ -142,7 +142,7 @@ pip install -r requirements-dev.txt
 
 There are several principles to follow when writing unit tests:
 
-- The test file path should be consistent with the source file and start with the `test_` prefix, such as: `vllm_ascend/worker/worker_v1.py` --> `tests/ut/worker/test_worker_v1.py`
+- The test file path should be consistent with the source file and start with the `test_` prefix, such as: `vllm_ascend/worker/worker.py` --> `tests/ut/worker/test_worker.py`
 - The vLLM Ascend test uses unittest framework. See [here](https://docs.python.org/3/library/unittest.html#module-unittest) to understand how to write unit tests.
 - All unit tests can be run on CPUs, so you must mock the device-related function to host.
 - Example: [tests/ut/test_ascend_config.py](https://github.com/vllm-project/vllm-ascend/blob/main/tests/ut/test_ascend_config.py).