Pass ENSO_LAUNCHER in docker, if present (#12418)

Passing `ENSO_LAUNCHER=native` will use native image for language
server.

tools/ci/docker/engine/Dockerfile

@@ -10,6 +10,7 @@ ARG PRINT_VERSION=0
 ARG JAVA_OPTS="-XX:MaxRAMPercentage=90.0 -XX:InitialRAMPercentage=90.0"
 ARG PROFILING_FILENAME
 ARG PROFILING_TIME
+ARG ENSO_LAUNCHER
 
 RUN useradd -u 2000 -c 'Enso Developer' -U -m ensodev
 
@@ -65,6 +66,7 @@ ENV YDOC_PORT=${YDOC_PORT}
 ENV LOG_LEVEL=${LOG_LEVEL}
 ENV PRINT_VERSION=${PRINT_VERSION}
 ENV JAVA_OPTS=${JAVA_OPTS}
+ENV ENSO_LAUNCHER=${ENSO_LAUNCHER}
 
 EXPOSE ${RPC_PORT}
 EXPOSE ${DATA_PORT}