Wrong source packaging in ha-singleton-deployment and resteasy-jaxrs-client

All of the JBoss EAP product quickstarts use the same packaging `org.jboss.as.quickstarts`.

The `resteasy-jaxrs-cient` uses `org.wildfly.quickstart` for the source packaging. Note the singular 'quickstart' in addition to `wildfly`.
The new `ha-singleton-deployment` quickstart uses `org.wildfly.quickstarts` for the source packaging.

We have always tried to make the quickstarts consistent for our uses and have provided these guidelines: https://github.com/jboss-developer/jboss-developer-shared-resources/blob/master/guides/CONTRIBUTING.md#general-guidelines

These quickstarts need to use the same packaging as the the product quickstarts. It looks more professional and will be less confusing for our customers.