Add net core and code coverage results (#77)

#### Why I did it

Publish code coverage results

#### How I did it

Modify azure pipeline yml file to install net core and publish code coverage results via Cobertura

#### How to verify it

Check code coverage

azure-pipelines.yml

@@ -78,6 +78,15 @@ stages:
         sudo dpkg -i ../target/debs/buster/libyang*1.0.73*.deb
       displayName: "Install dependency"
 
+    - script: |
+        set -ex
+        # Install .NET CORE
+        curl -sSL https://packages.microsoft.com/keys/microsoft.asc | sudo apt-key add -
+        sudo apt-add-repository https://packages.microsoft.com/debian/10/prod
+        sudo apt-get update
+        sudo apt-get install -y dotnet-sdk-5.0
+      displayName: "Install .NET CORE"
+
     - script: |
         set -ex
         ls -l
@@ -93,7 +102,17 @@ stages:
         dpkg-buildpackage -rfakeroot -us -uc -b -j$(nproc) && cp ../*.deb $(Build.ArtifactStagingDirectory)/
       displayName: "Build"
 
+    - script: |
+        pushd sonic-gnmi
+        make check
+      displayName: "Test"
+
     - publish: $(Build.ArtifactStagingDirectory)/
       artifact: sonic-telemetry
       displayName: "Archive artifacts"
 
+    - task: PublishCodeCoverageResults@1
+      inputs:
+              codeCoverageTool: Cobertura
+              summaryFileLocation: '$(System.DefaultWorkingDirectory)/sonic-gnmi/coverage.xml'
+      displayName: 'Publish coverage'