single executable jbang-based junit test class

[blafond]

targets issue #721

FIrst pass at a single junit test class that's executable by jbang CLI

[DavideD]

Thanks @blafond!

It needs some minor improvements to the way it's documented but overall it looks good to me.
An alternative would be to create something closer to what we do for the examples.

I've created a quick POC here: https://github.com/DavideD/hibernate-reactive/blob/721-jbang-executable-test/tooling/jbang/Example.java

If you want to see them in action, here's how it works:

1. Download JBang
2. Start the default Postgres we use for testing (you can replace podman with docker):

   podman run --rm --name HibernateTestingPGSQL \
   -e POSTGRES_USER=hreact -e POSTGRES_PASSWORD=hreact -e POSTGRES_DB=hreact \
   -p 5432:5432 postgres:13.2
   

3. JBang it:

   jbang https://github.com/DavideD/hibernate-reactive/blob/721-jbang-executable-test/tooling/jbang/Example.java
   

   or

   jbang https://github.com/blafond/hibernate-reactive/blob/721-jbang-executable-test/tooling/jbang/SampleIssueTest.java
   

4. (Optional) If you want to edit the class with Idea

   jbang edit --open=idea https://github.com/blafond/hibernate-reactive/blob/721-jbang-executable-test/tooling/jbang/SampleIssueTest.java
   

Not sure which one I prefer. Maybe we can keep both? The JUnit one could be helpful to show how one can test Hibernate Reactive (maybe we can make it make it slightly more complex and add a couple of tests instead of only keep one) while the example one might be more familiar to the user and we can keep it simpler.

Note that I've asked @blafond to not create a template for now (because it makes it slightly harder to prototype with them). I think it makes sense to convert these classes to JBang templates ones we are happy with them and we can send a pr to JBang to add them to the catalogue.

@gavinking What do you think?
@gbadner, @Sanne In case you are interested and want to see an example of JBang in action

Cheers

[DavideD]

Thanks,
looks pretty good.

We can play a bit more with this in the future, but I think this is a good starting point.
I will probably change a couple of minor things when working on the contribution guide.

In particular, I wouldn't keep a separate README for this. But we can change it later.