CHORE: CodeQL ADO pipeline task (#259)

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[AB#38859](https://sqlclientdrivers.visualstudio.com/c6d89619-62de-46a0-8b46-70b92a84d85e/_workitems/edit/38859)


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### Summary   
This pull request adds a new CodeQL security analysis job to the
`pr-validation-pipeline.yml` to improve automated security scanning of
the codebase. The changes introduce a dedicated container for the CodeQL
job, install necessary dependencies, and ensure the C++ extension is
built for analysis.

**Security and CI pipeline enhancements:**

* Added a new `CodeQLAnalysis` job to the pipeline to perform CodeQL
security analysis, including initialization and finalization steps.
* Introduced a `codeqlContainer` using the `ubuntu:20.04` image to
provide a consistent environment for CodeQL analysis.
* Added steps to install build dependencies and Python 3.13, and to
install Python requirements needed for CodeQL.
* Included a step to build the C++ extension
(`mssql_python/pybind/build.sh`) as part of the CodeQL analysis process.

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Author: bewithgaurav

eng/pipelines/pr-validation-pipeline.yml

@@ -7,6 +7,44 @@ trigger:
       - main
 
 jobs:
+- job: CodeQLAnalysis
+  displayName: 'CodeQL Security Analysis'
+  pool:
+    vmImage: 'ubuntu-latest'
+  
+  steps:
+  - script: |
+      sudo apt-get update
+      sudo apt-get install -y build-essential cmake curl git python3 python3-pip python3-dev python3-venv unixodbc-dev
+    displayName: 'Install build dependencies for CodeQL'
+
+  - task: UsePythonVersion@0
+    inputs:
+      versionSpec: '3.13'
+      addToPath: true
+    displayName: 'Use Python 3.13 for CodeQL'
+
+  - script: |
+      python -m pip install --upgrade pip
+      pip install -r requirements.txt
+    displayName: 'Install Python dependencies for CodeQL'
+
+  - task: CodeQL3000Init@0
+    inputs:
+      Enabled: true
+    displayName: 'Initialize CodeQL'
+
+  # Build the C++ extension for CodeQL analysis
+  - script: |
+      cd mssql_python/pybind
+      chmod +x build.sh
+      ./build.sh
+    displayName: 'Build C++ extension for CodeQL analysis'
+
+  - task: CodeQL3000Finalize@0
+    condition: always()
+    displayName: 'Finalize CodeQL'
+
 - job: PytestOnWindows
   displayName: 'Windows x64'
   pool: