Add Dockerfile for CD of Docker images in the Master branch

Dockerfile

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+# This is a Dockerfile definition for Experimental Docker builds.
+# DockerHub: https://hub.docker.com/r/jenkins/jenkins-experimental/
+# If you are looking for official images, see https://github.com/jenkinsci/docker
+FROM maven:3.5.4-jdk-8 as builder
+
+COPY .mvn/ /jenkins/src/.mvn/
+COPY cli/ /jenkins/src/cli/
+COPY core/ /jenkins/src/core/
+COPY src/ /jenkins/src/src/
+COPY test/ /jenkins/src/test/
+COPY war/ /jenkins/src/war/
+COPY *.xml /jenkins/src/
+COPY LICENSE.txt /jenkins/src/LICENSE.txt
+COPY licenseCompleter.groovy /jenkins/src/licenseCompleter.groovy
+COPY show-pom-version.rb /jenkins/src/show-pom-version.rb
+
+WORKDIR /jenkins/src/
+RUN mvn clean install --batch-mode -Plight-test
+
+# The image is based on the previous weekly, new changes in jenkinci/docker are not applied
+FROM jenkins/jenkins:latest
+
+LABEL Description="This is an experimental image for the master branch of the Jenkins core" Vendor="Jenkins Project"
+
+COPY --from=builder /jenkins/src/war/target/jenkins.war /usr/share/jenkins/jenkins.war
+ENTRYPOINT ["tini", "--", "/usr/local/bin/jenkins.sh"]