feat: move build cmds to script, generate custom jre

build.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/sh -eu
+
+export PATH="$PWD/jdk/bin:$PATH"
+export JAVA_HOME="$PWD/jdk"
+
+# check if JDK works
+java --version
+
+# build TESLauncher
+cd src
+./gradlew shadowJar
+cd ..
+
+# install built JAR named TESLauncher-x.y.z.jar
+find src/build/libs/ -name "TESL*.jar" -type f -exec \
+  install -D -m 644 {} /app/tesl.jar \;
+#
+
+# generate JRE with all modules enabled
+jlink \
+  --strip-debug --no-man-pages --no-header-files --compress=2 \
+  --add-modules ALL-MODULE-PATH --output jre
+#
+
+# check if JRE works
+./jre/bin/java --version
+
+# install JRE
+mkdir -p /app/lib/jvm/openj9
+cp -r ./jre/* /app/lib/jvm/openj9