[Build] Add support for Ascend950 chip (#7151)

### What this PR does / why we need it?
This PR adds support for the Ascend950 chip. This includes:
- Updating build scripts (`CMakeLists.txt` and `setup.py`) to recognize
the Ascend950 chip and set appropriate compilation flags.
- Disabling a set of custom operators that are not yet supported on the
Ascend950 hardware target.
- Performing a codebase-wide refactoring of `pipe_barrier()` calls to
the namespaced `AscendC::PipeBarrier<>()` for improved code consistency
and adherence to the latest API standards.

Ascend950DT e2e passed (Qwen3-32B-MXFP8) and CI passed
- vLLM version: v0.16.0
- vLLM main:
4034c3d32e
---------
Signed-off-by: linfeng-yuan <1102311262@qq.com>

vllm_ascend/utils.py

@@ -267,7 +267,10 @@ def enable_custom_op():
 
     # There are some customed operators which aren't implemented
     # with batch invariant in vllm-ascend, we need to disable them.
-    if vllm_is_batch_invariant():
+    # FIXME(linfeng): Currently custom op compilation and execution are partially available
+    # in ASCEND950 chip, we temporarily disable all custom ops. Please refer to
+    # https://github.com/vllm-project/vllm-ascend/issues/7157 for latest update about custom op.
+    if vllm_is_batch_invariant() or get_ascend_device_type() == AscendDeviceType.A5:
         _CUSTOM_OP_ENABLED = False
         return _CUSTOM_OP_ENABLED