Add a method to use producer in entity resource

[fdelbrayelle]

Overview of the feature request

The generated producers should be used in resources at least to allow to test them alongside with consumers.

As consumers are standalone and consume data that are logged it won't be necessary for them to be added in resources.

⚠️ Generated producers for a given generated entity can be used in EntityResource.java.ejs that will be extended in the module but this is not the case for producers not linked to a generated entity. In this case, maybe a PrefixResource.java.ejs could be created to do the work.

Motivation for or Use Case

Be able to use and test producers alongside with consumers.

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