feat(examples): Introduce Hello in Java as example

Introduce a Hello Java program as binary compatibility run. Install Java
and build program using `Dockerfile`. Then run it with the `base` kernel
images from `../../kernels/`.

Add typical files for a bincompat app:

* `Kraftfile`: build / run rules, including pulling the `base` image
* `Dockerfile`: filesystem, including binary and libraries
* `Makefile`: used to generate the root filesystem from the `Dockerfile`
  rules
* `README.md`: instructions to set up, build and run the application
* `config.yaml`: configuration file to generate scripts to the
  application
* `Hello.java`: the Java program

`config.yaml` is used to generate run scripts using the
`../../utils/bincompat/generate.py` script.

The kernels in `../../kernels` are generated by running the
`../../utils/bincompat/base-build-all.sh` script while inside the
`../../library/base/` directory.

Signed-off-by: Razvan Deaconescu <[email protected]>

examples/hello-java17/.gitignore

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+/rootfs/
+/rootfs.cpio
+/run-qemu*
+/run-fc*
+/kraft-run-*
+/fc*.json

examples/hello-java17/Dockerfile

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+FROM  --platform=linux/x86_64 debian:bookworm AS build
+
+RUN set -xe ; \
+    apt -yqq update ; \
+        apt -yqq install default-jre ; \
+        apt -yqq install default-jdk
+
+WORKDIR /src
+
+COPY ./Hello.java /src/Hello.java
+
+RUN javac Hello.java
+
+FROM scratch
+
+COPY --from=build /lib/x86_64-linux-gnu/libc.so.6 /lib/x86_64-linux-gnu/libc.so.6
+COPY --from=build /lib/x86_64-linux-gnu/libstdc++.so.6 /lib/x86_64-linux-gnu/libstdc++.so.6
+COPY --from=build /lib/x86_64-linux-gnu/libm.so.6 /lib/x86_64-linux-gnu/libm.so.6
+COPY --from=build /usr/lib/x86_64-linux-gnu/libz.so.1 /usr/lib/x86_64-linux-gnu/libz.so.1 
+COPY --from=build /lib/x86_64-linux-gnu/libgcc_s.so.1 /lib/x86_64-linux-gnu/libgcc_s.so.1
+COPY --from=build /lib64/ld-linux-x86-64.so.2 /lib64/ld-linux-x86-64.so.2
+
+COPY --from=build /usr/lib/jvm/java-17-openjdk-amd64 /usr/lib/jvm/java-17-openjdk-amd64
+COPY --from=build /usr/lib/jvm/java-17-openjdk-amd64/lib/libjli.so /lib/x86_64-linux-gnu/libjli.so 
+
+COPY --from=build /src/Hello.class /Hello.class

examples/hello-java17/Hello.java

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+public class Hello {
+	public static void main(String[] args) {
+		System.out.println("Hello, World!");
+	}
+}

examples/hello-java17/Kraftfile

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+spec: v0.6
+
+name: hello-java
+
+runtime: index.unikraft.io/unikraft.org/base:latest
+
+rootfs: ./Dockerfile
+
+cmd: ["/usr/lib/jvm/java-17-openjdk-amd64/bin/java", "Hello"]

examples/hello-java17/Makefile

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+IMAGE_NAME = unikraft-java
+CMD = /usr/lib/jvm/java-17-openjdk-amd64/bin/java Hello
+
+include ../../utils/bincompat/docker.Makefile

examples/hello-java17/README.md

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+# Hello World on Java
+
+This directory contains the definition to run a helloworld program with [Python3](https://www.python.org/) on Unikraft in binary compatibility mode.
+
+Follow the instructions in the common `README.maintainers.md` file in the root of the repository to set up and configure the application.
+
+## Quick Run
+
+Use `kraft` to run the image:
+
+```console
+kraft run -M 512M
+```
+
+Once executed, it will run the `helloworld.py` script and print "Hello, World!".
+
+## Scripted Run
+
+Use the scripted runs, detailed in the `README.maintainers.md` file.
+Once executed, scripts will run the `helloworld.py` script and print "Hello, World!".

examples/hello-java17/config.yaml

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+networking: False
+accel: True
+memory: 1048
+kerneldir: ../../kernels