Configured Jenkins (#1127)

Added a Jenkins configuration file for a build pipeline using gradle.

- Runs tests
- Run checkstyle
- Runs sonar and publishes to SonarCloud

Jenkinsfile

@@ -0,0 +1,39 @@
+pipeline {
+    agent any
+
+    stages {
+        stage('Test') {
+            steps {
+                dir("Plan") {
+                    script {
+                        try {
+                            sh './gradlew clean test --no-daemon' //run a gradle task
+                        } finally {
+                            junit '**/build/test-results/test/*.xml' //make the junit test results available in any case (success & failure)
+                        }
+                    }
+                }
+            }
+        }
+        stage('Checkstyle') {
+            steps {
+                dir("Plan") {
+                    script {
+                        sh './gradlew checkstyleMain checkstyleTest'
+                    }
+                }
+            }
+        }
+        stage('SonarQube analysis') {
+            steps {
+                dir("Plan") {
+                    script {
+                        withSonarQubeEnv() {
+                            sh './gradlew sonarqube -Dsonar.organization=player-analytics-plan'
+                        }
+                    }
+                }
+            }
+        }
+    }
+}