Mark Lucene, Elasticsearch REST client, GSON as public modules

These modules were originally only added for internal use within in Hibernate Search, so they were marked with "jboss.api"="private".

However, while it's not strictly necessary for developers to access these classes in order to use
Hibernate Search, it can still be useful. For example, they can native Lucene queries using the Lucene dependency or native Elasticsearch queries using the GSON dependency.

For these reasons, I think we should expose these modules as "public" instead of "private".

Note however that, due to our lack of control over the backwards compatibility of Lucene, GSON and Elasticsearch APIs, these modules probably won't be supported in EAP, so we'll have to mark the modules with "jboss.api"="unsupported" there (see JBEAP-23919 )