add wildfly.yaml to JMX scraper

[SylvainJuge]

Description:

• add wildfly support for jmx scraper with dedicated YAML configuration
• adds wildfly tests using jboss-client.jar for using HTTP management API
• fixes support for login/pwd authentication
• adds a test webapp needed to test wildfly session metrics
• moves existing test app to dedicated module for simplicity (and making it similar to test webapp)
• fixes use of plural form in units in wildfly.groovy to fit the stable convention for metric units.

Part of #1362

Notes:

In the original groovy implementation session metrics are not tested, this requires deploying and application to the container, this is not properly tested in the YAML implementation.

In the original groovy implementation the gatherer was run directly from the same docker container probably for simplicity as jboss-client.jar is directly available.
When using two containers, the jar needs to be copied from wildfly container to scraper container and it complicates authentication: login/pwd can be skipped if both processes run on the same host and can access the same filesystem.
Testing here is done using two distinct containers as this setup is a bit more complex and thus likely to fail (doing so here helped me find that we did not handle it properly).

[SylvainJuge]

[for reviewer] waiting for open port seems to sometimes not be accurate enough to detect proper startup, which makes the scraper container start when the JMX port is not yet available. Waiting on log message is an attempt to make this a bit less flaky (time will tell if that's a good idea or not here).

[robsunday]

Wait.forListeningPort() requires withExposedPorts(jmxPort) to be called to work properly. I think Tomcat test works by a chance. I added withExposedPorts to all tests using forListeningPort on my branch, but you can add it in your PR instead

[SylvainJuge]

While this sounds brittle, I think it's slightly better to wait for the target application to be properly started (here we use the log message as a proxy), because while the JMX port might be open early, the MBeans are likely not yet published so while we can connect to it the MBeans that we are trying to access are likely not yet published.

Otherwise do you suggest to add to every container something like this for Tomcat:

  protected GenericContainer<?> createTargetContainer(int jmxPort) {
    return new GenericContainer<>(
        new ImageFromDockerfile()
        // ...
        .withStartupTimeout(Duration.ofMinutes(2))
        .withExposedPorts(8080, jmxPort)
        .waitingFor(Wait.forListeningPorts(8080, jmxPort));
  }

[SylvainJuge]

As discussed today I've implemented it for all other containers in 3ab2f28.