add vitisai ep build stage to Windows CPU Pipeline (microsoft#21361)

We need to prevent VitisAI EP build breaks, add a stage in Windows CPU
CI Pipeline to build Vitis AI EP on Windows.
There are no external dependencies for builds. Tests have to be disabled
though as the EP has external SW/HW dependencies.
This will at least allow us to prevent build breaks which has happened
on multiple occasions recently.

tested
https://dev.azure.com/onnxruntime/onnxruntime/_build/results?buildId=1432346&view=results
and it seems to run fine.

Author: jywu-msft

tools/ci_build/github/azure-pipelines/win-ci-pipeline.yml

@@ -137,6 +137,25 @@ stages:
         WITH_CACHE: false
         MachinePool: 'onnxruntime-Win-CPU-2022'
 
+# Build only. Does not run any tests.
+- stage: x64_release_vitisai
+  dependsOn: []
+  jobs:
+    - template: templates/jobs/win-ci-vs-2022-job.yml
+      parameters:
+        BuildConfig: 'RelWithDebInfo'
+        buildArch: x64
+        additionalBuildFlags: --build_wheel --use_vitisai
+        msbuildPlatform: x64
+        isX86: false
+        job_name_suffix: x64_release
+        RunOnnxRuntimeTests: false
+        isTraining: false
+        ORT_EP_NAME: VITISAI
+        GenerateDocumentation: false
+        WITH_CACHE: false
+        MachinePool: 'onnxruntime-Win-CPU-2022'
+
 - stage: x64_release_winml
   dependsOn: []
   jobs: