Speed-up initialization of action

by using the built image of scanner CLI

Dockerfile

@@ -1,4 +1,4 @@
-FROM openjdk:11-jre-slim
+FROM sonarsource/sonar-scanner-cli:4.3
 
 LABEL version="0.0.1"
 LABEL repository="https://github.com/sonarsource/sonarcloud-github-action"
@@ -12,29 +12,12 @@ LABEL "com.github.actions.color"="green"
 ARG SONAR_SCANNER_HOME=/opt/sonar-scanner
 ARG NODEJS_HOME=/opt/nodejs
 
-ENV SONAR_SCANNER_HOME=${SONAR_SCANNER_HOME} \
-    SONAR_SCANNER_VERSION=3.3.0.1492 \
-    NODEJS_HOME=${NODEJS_HOME} \
-    NODEJS_VERSION=v8.12.0
-
 ENV PATH=${PATH}:${SONAR_SCANNER_HOME}/bin:${NODEJS_HOME}/bin
 
 WORKDIR /opt
 
-RUN apt-get update \
-    && apt-get install -y --no-install-recommends wget git jq unzip tar xz-utils \
-    && rm -rf /var/lib/apt/lists/*
-
-RUN wget -U "sonarcloud-github-action" -q -O sonar-scanner-cli.zip https://binaries.sonarsource.com/Distribution/sonar-scanner-cli/sonar-scanner-cli-${SONAR_SCANNER_VERSION}.zip \
-    && unzip sonar-scanner-cli.zip \
-    && rm sonar-scanner-cli.zip \
-    && mv sonar-scanner-${SONAR_SCANNER_VERSION} ${SONAR_SCANNER_HOME}
-
-RUN wget -q -O nodejs.tar.xz https://nodejs.org/dist/${NODEJS_VERSION}/node-${NODEJS_VERSION}-linux-x64.tar.xz \
-    && tar -Jxf nodejs.tar.xz \
-    && mv node-${NODEJS_VERSION}-linux-x64 ${NODEJS_HOME}
-
-RUN npm install -g typescript
+# https://help.github.com/en/actions/creating-actions/dockerfile-support-for-github-actions#user
+USER root
 
 COPY entrypoint.sh /entrypoint.sh
 RUN chmod +x /entrypoint.sh