chore(WIP): Proof of concept demo GraalVM Kokoro Scripts

[dzou]

This PR introduces GraalVM integration testing.

@Neenu1995 @lesv

[generated-files-bot]

Warning: This pull request is touching the following templated files:

• .kokoro/build.sh

[lesv]

@dzou Are you asking for a review? build.sh is templated and once you have something that works, we can help you modify the templates to distribute it everywhere.

[lesv]

The pom.xml is probably also templated.

[dzou]

@dzou Are you asking for a review? build.sh is templated and once you have something that works, we can help you modify the templates to distribute it everywhere.

Hey @lesv, @Neenu1995 -- Sorry for any confusion. I just wanted to create this PR to see if the GraalVM Kokoro Job would build and run successfully in the presubmit.

I think we have a success for the GraalVM kokoro run:

Here is the link: https://source.cloud.google.com/results/invocations/3639ad3e-8411-49e4-9c01-382bda6b00b2/targets

I think this PR is a good summary of the changes we would need to make (no need to for a full merge to run the tests). Thoughts on the next steps? Maybe you may be amenable to me updating the templates -- It seems like it might be possible to add the changes to the templates and extend things cleanly: changing both the build.sh and pom.xml should be a no-op, and I think it's only the addition of the graalvm-native.cfg which opts-in a repository for GraalVM testing (which can be done one-by-one for each repository to opt-in slowly).