Test that deploy to maven central succeeded (release workflow)

[EricWittmann]

Add a step to the release workflow where we verify that the artifacts were actually deployed properly to maven central. At a minimum we should have a simple test/demo maven project that we can use to build and verify that the appropriate artifacts are available.

[jsenko]

Can we build the examples repo after the release, so we don't have to use a separate test repo. We can add a profile to the examples that would make sure all artifacts are downloaded.

[EricWittmann]

So I think what we can do here is twofold:

1. A basic curl command that tries to download one or two of the artifacts using a direct URL to maven central
2. We can create a basic standalone maven project (this can be just a pom.xml really) that pulls in one or more Apicurio Registry artifacts as dependencies - once the push is done we can clean out the local .m2/repository equivalent and then mvn package the test project

Note that for (1) the URL can be something like this (for example):

https://repo.maven.apache.org/maven2/io/apicurio/apicurio-registry-client/$RELEASE_VERSION/apicurio-registry-client-$RELEASE_VERSION.pom

If the push failed then this would result in a 404. Otherwise it will work.

[riprasad]

Are we going to do both or just the curl command would be sufficient? @EricWittmann

[riprasad]

Also, Instead of including the steps in the release workflow, I would suggest that we should have a third workflow verify-release.yaml where we could verify both the docker push and deploy to maven central. WDYT @EricWittmann @jsenko

[EricWittmann]

I think we should do both the curl and the sample project. The curl goes first as a quick smoke test, and then building the sample project as a more thorough test.

I'm fine with a separate workflow.